EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: nbritton on September 11, 2015, 03:22:04 am
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I find the hacked Rigol 1054Z very compelling. However, decoding SPI on this scope is limited to 25 MHz. Is there a better bang for your buck scope if your primary interest is computer engineering? Would it be better to get the 1054Z + logic analyzer + function generator, or put the money towards a MSO that can do all of those things? Besides the basics discussed in EEVblog #168, what other test equipment is fundamental for a computer engineering lab? This is just a hobby for me and also I'm living in a small apartment right now. I'm a linux engineer by day, if I can frame this as professional development I think I can budget what is necessary to get the right equipment. One of the things I'd love to do is build my own 1970s era computer from scratch so that I can further my understanding of computers. I'd also like to be able to interface with things like Raspberry Pis and other Linux based SBCs for embedded system design.
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The decoding functions on the DS1054z are pretty meh, as well as the fft, but the scope is a great value all around. MSOs are nice but expensive. Your first plan consisting of the three separate pieces of test equipment will yield better value. I think Saleae products are still great, but you can find cheaper analyzers.
I think it's fine to buy necessary components like multimeters and scopes, and in your case logic analyzers initially, but I don't see a point in buying everything at once. You can end up with a bunch of stuff that sits around, and not have enough money to buy things you realize you need or want after you get started. It would be wiser to buy things as you require them.
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I give :-+ to one of the Saleae logic pro models. I think a logic analyser will probably be more useful to you than a 2 ch analog scope. With logic pro you get some basic analog features too, but very decent signal decoding, and many channels, which is very handy debugging code and digital systems.
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Get a dedicated logic analyzer if that's your thing.
The DS1054Z is only good for very basic logic analysis. The MSO versions aren't much better. You really need a mouse, keyboard and gigabytes of RAM for serious logic analysis (eg. Saleae).
You also need a 'scope to look at signal integrity on your data lines. Saleae and DS1054Z.
PS: Did 1970s computers have SPI?
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Would you guys pick a hacked DS2072A for $839 or a hacked DS1054Z for $399?
The DS2072A is 2-Channel, 300 MHz, 2 Gs/s, 56 Mpts, 500uV, 50 Ohm Input
The DS1054Z is 4-Channel, 100 MHz, 1 Gs/s, 24 Mpts
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Would you guys pick a hacked DS2072A for $839 or a hacked DS1054Z for $399?
The DS2072A is 2-Channel, 300 MHz, 2 Gs/s, 56 Mpts, 500uV, 50 Ohm Input
The DS1054Z is 4-Channel, 100 MHz, 1 Gs/s, 24 Mpts
Subtract 6% with the EEVBlog discount @ Tequipment.
I have both of those scopes. I prefer the DS2000 as it has a larger screen, higher sample rate, higher bandwidth, 50ohm input impedance, a really nice jog dial for segmented memory, and more. Personally, I'd go with the DS2000 + a newer model Saleae (one of the FPGA-driven versions).
Edit: The DS2000 also lets you hide the side menus, which gives you more horizontal divisions. This is one of my favorite options on the scope.
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Would you guys pick a hacked DS2072A for $839 or a hacked DS1054Z for $399?
I have both of those scopes. I prefer the DS2000
I should hope so! It costs twice as much, something would be seriously wrong if you preferred the cheap one.
(Although sometimes you *do* need four channels, eg. for decoding SPI :) In that case the cheap one is preferable.)
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However, decoding SPI on this scope is limited to 25 MHz.
There's a strong argument you should not decode SPI on an oscilloscope:
- adding the scope may change the analogue signal
- the scope may interpret (i.e. digitise) the analogue signal in a different way to the "real" reciever
- use analogue tools for analogue signals, and digital tools for digital signals
Thus:
- if you are looking at signal integrity, then use an analogue scope
- if you are looking at bits and bytes, use a logic analyser or log things using software
But "never say never" :)
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Get a dedicated logic analyzer if that's your thing.
The DS1054Z is only good for very basic logic analysis. The MSO versions aren't much better. You really need a mouse, keyboard and gigabytes of RAM for serious logic analysis (eg. Saleae).
You also need a 'scope to look at signal integrity on your data lines. Saleae and DS1054Z.
PS: Did 1970s computers have SPI?
It's worth also considering the sample rate of the LA: many USB analysers are quite low sample rates (100MHz is common for example). This may or may not be a problem depending on what you're doing.
Maybe I'm weird, but I rarely use a USB LA, almost always I use an MSO. I used to use my Logicport quite extensively, but once I had an scope with serial decode and triggering, it maybe comes out once a year, and that's for the rare occasions I need to look at parallel busses. The reason might be because the scope's always out on the desk and ready to go with the pods and probes attached, whereas the LA is typically stored in a drawer under the desk.
In the '70s, everything was parallel busses for intra- and inter-board connections. I think the first time I saw I2C was in the early/mid '80s. Back then, 100kbps seemed awesome! I don't remember SPI catching on generally for some time after that, but others may have differing recollections.
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There's a strong argument you should not decode SPI on an oscilloscope:
- adding the scope may change the analogue signal
- the scope may interpret (i.e. digitise) the analogue signal in a different way to the "real" reciever
- use analogue tools for analogue signals, and digital tools for digital signals
Sorry, but I am not buying into those arguments. Number 1 and 2 apply to any digital logic analyser as well, and number 3 is not a technical argument at all. I do agree that a PC-based logic analyser is preferrable for digital signal analysis and decoding, but for different reasons: Larger screen, larger memory.
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There's a strong argument you should not decode SPI on an oscilloscope:
- adding the scope may change the analogue signal
- the scope may interpret (i.e. digitise) the analogue signal in a different way to the "real" reciever
- use analogue tools for analogue signals, and digital tools for digital signals
Sorry, but I am not buying into those arguments. Number 1 and 2 apply to any digital logic analyser as well, and number 3 is not a technical argument at all. I do agree that a PC-based logic analyser is preferrable for digital signal analysis and decoding, but for different reasons: Larger screen, larger memory.
To repeat my statement that you snipped: 'But "never say never" :)'
In practice, if you follow 3 then a beginner will make far fewer mistakes of the type that can and do arise from 1 and 2.
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The MSO2072A costs $376 more than the DS2072A, is the build-in logic analyzer worth $376? How does it compare to USB based LAs, such as the Saleae? The 16 channel Saleae with 100 MHz bandwidth costs $599. The cheapest 8 channel Saleae with 25 MHz bandwidth is $219.
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Perhaps another way of looking at this is that given the choice of an LA and a scope, I'd always take the scope.
Given the choice between a 2Gsa/s 300MHz 2ch scope and a 1Gsa/s 100MHz 4ch scope is a little harder, but overall I think I'd go for the 100MHz 4 ch scope.
But given the choice between a 300MHz 2+16ch MSO and a 100MHz 4ch scope I'd take the 300MHz 2+16ch MSO.
My line of work is embedded mixed signal RF, with about 65% MCU (up to 200MHz clock) and the rest analogue, so I am sure others may have different opinions.
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The MSO2072A costs $376 more than the DS2072A, is the build-in logic analyzer worth $376? How does it compare to USB based LAs, such as the Saleae? The 16 channel Saleae with 100 MHz bandwidth costs $599. The cheapest 8 channel Saleae with 25 MHz bandwidth is $219.
USB is much better because it has bigger screen (your PC!), more memory, better controls for zooming and panning, etc. Twiddling knobs on a 'scope just doesn't work as well as a mouse/keyboard. I'd say get the DSO + a Saleae (or equivalent)
Edit: Unless you don't have a PC on your workbench, obviously...
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I have a Logic Pro 16, great hardware, almost-great software hobbled by crashing every acquisition. The only software that supports the new models is BETA.
Also, though the pro has ADCs on every pin, the sample rate is dog-slow and is barely even sufficient to look at i2c.
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I don't like the USB logic analysers because either the memory is short or the sample rate low. A modern MSO (preferably with protocol with decoding) is much more useful.
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I have a Logic Pro 16, great hardware, almost-great software hobbled by crashing every acquisition. The only software that supports the new models is BETA.
Also, though the pro has ADCs on every pin, the sample rate is dog-slow and is barely even sufficient to look at i2c.
I'm intrigued by this post because I'm struggling to stick a crowbar in my wallet and spring for the Pro 16. I thought the software was supposed to be far better than the competition. Maybe not the new (beta) stuff then, huh? How do you feel about their ability to sort it out?
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I don't like the USB logic analysers because either the memory is short or the sample rate low. A modern MSO (preferably with protocol with decoding) is much more useful.
I find this odd myself ;) , but I prefer a scope to be standalone, and a logic analyzer to be USB type.
Maybe because the different type of manipulations I do with each of them?
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I have a Logic Pro 16, great hardware, almost-great software hobbled by crashing every acquisition. The only software that supports the new models is BETA.
Also, though the pro has ADCs on every pin, the sample rate is dog-slow and is barely even sufficient to look at i2c.
I'm intrigued by this post because I'm struggling to stick a crowbar in my wallet and spring for the Pro 16. I thought the software was supposed to be far better than the competition. Maybe not the new (beta) stuff then, huh? How do you feel about their ability to sort it out?
They're coming up on one year with software still in beta. My Pro-16 shipped Oct 8 last year and I'm still waiting for released software.
I agree with marshallh that the ADC per channel is a big disappointment due to its slow acquisition rate. It's no substitute for even the worst scope. I'm sure it added quite a bit to the cost.
I also have an old Logic 8 which I tend to use more. It's smaller and less bulky, and it runs with the older released software (1.1.15) which is rock solid. At the moment, I'd recommend getting one of those, or the old 16-input model if you can find one. Both have been discontinued.
In my opinion, Saleae has spent way too much time making their UI slick and pretty, and they lost sight of making it functional first.
On the plus side, they continue to be active and responsive to bug reports, so I think they'll get there eventually, but I would wait on a Pro purchase. I regret jumping in so early.
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I don't like the USB logic analysers because either the memory is short or the sample rate low. A modern MSO (preferably with protocol with decoding) is much more useful.
I find this odd myself ;) , but I prefer a scope to be standalone, and a logic analyzer to be USB type.
Maybe because the different type of manipulations I do with each of them?
The reasoning behind it is that an MSO usually has deeper memory and faster scrolling etc.
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I don't like the USB logic analysers because either the memory is short or the sample rate low. A modern MSO (preferably with protocol with decoding) is much more useful.
I find this odd myself ;) , but I prefer a scope to be standalone, and a logic analyzer to be USB type.
Maybe because the different type of manipulations I do with each of them?
The reasoning behind it is that an MSO usually has deeper memory and faster scrolling etc.
Deeper memory than a PC? ???
<snip>
<snip>
<snip>
Thank you both immensely for your thoughts. I'll direct my resources toward other priorities for now and revisit later.
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I don't like the USB logic analysers because either the memory is short or the sample rate low. A modern MSO (preferably with protocol with decoding) is much more useful.
I find this odd myself ;) , but I prefer a scope to be standalone, and a logic analyzer to be USB type.
Maybe because the different type of manipulations I do with each of them?
The reasoning behind it is that an MSO usually has deeper memory and faster scrolling etc.
Deeper memory than a PC? ???
Definitely at higher samplerates.
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Dave made a video about this: https://www.youtube.com/watch?v=MC9_4mpqVgU (https://www.youtube.com/watch?v=MC9_4mpqVgU)
Also, I personally don't think the hardware in an MSO makes up for the fact that you have to use the LA through the scope interface.
The best scenario is where both the hardware and software are the best, such as in a Windows based scope, but those are out of most hobbyist budgets.
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I guess I am misunderstanding something perhaps, I only have the first model Logic 16, not the pro, but their website says 50MS/s for analog and 500MS/s for digital. Is there some problem with the 500MS/s since everyone keeps saying the ADC is slow? I've used the 1.2.3 beta software and it is much improved over previous versions at least for me.
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I find the hacked Rigol 1054Z very compelling. However, decoding SPI on this scope is limited to 25 MHz.
I don't know about the analogue channels, but the MSO1000Z LA channels will decode 50MHz SPI, down to a 250MHz sample rate.
Edit: I just tried it on the analogue channels, and while the signals ain't pretty, it does decode fine on a 50MHz SPI stream.
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One of the points in favor of the USB LA was that you can view everything on a computer monitor. However, since the Rigol's have USB/Ethernet can't you also view these on a computer monitor too?
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I guess I am misunderstanding something perhaps, I only have the first model Logic 16, not the pro, but their website says 50MS/s for analog and 500MS/s for digital. Is there some problem with the 500MS/s since everyone keeps saying the ADC is slow?
The ADC is for analog.
I don't really know why they bother adding the analog stuff. Maybe it's useful to be able to see the analog signals alongside the digital for timing issues. The bandwidth is awful though.
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One of the points in favor of the USB LA was that you can view everything on a computer monitor. However, since the Rigol's have USB/Ethernet can't you also view these on a computer monitor too?
Yes but with the same number of pixels as the scope's screen. And with slower update rate.
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Hi,
The ADC is for analog.
I don't really know why they bother adding the analog stuff. Maybe it's useful to be able to see the analog signals alongside the digital for timing issues. The bandwidth is awful though.
I am with you, but you can choose analog or digital for each pin, and choose both. If you choose "digital" then you get 500MSa/s, right? Then it is using a comparator and not the ADC, right?
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In my opinion an Oscilloscope and a Logic Analyser are very different tools with different usage.
I use the oscilloscope primarily for ensuring signal integrity, does the waveform look right, is there noise etc. Once I know the signal looks good I might use it to ensure a few packets of data decode to what I expect and so its useful to have decoding on the scope.
I tend to prefer to use the PC based Logic Analyzer for decoding and examining large blocks of data, its more about the content of data streams than the shape of the signals. Its cumbersome working with tables of decoded data on an mixed signal oscilloscope, even if your scope supports plugging in a mouse and keyboard like the Agilent/Keysight scopes do. Yes you can copy data to PC from the scope, but those extra steps are not productive when your trying to fix a software problem.
You could consider a 4 ch Picoscope. They have very good decoding and free software updates. I doubt there is a stand alone scope that can decode a many different data types as the picoscope software does (and decode software is free). A USB scope is cumbersome in the opposite way the scope based LA is, but is compact and portable and they can have HUGE memory buffers (hundreds of MB) so you can drill into very long captures. You get all the benefits of a PC based LA, but not the number of channels, you really do need 4 or more. USB scopes take getting used to if your used to a scope. I forced myself for a while, but eventually the proper oscilloscope reappeared on my bench. Its very useful as a portable tool too, they are small and compact when your dragging a laptop or tablet around as well.
It comes down to what your predominately using it for, for maximum productivity you need the right tool for the job.
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Yeah I rarely use the analog channels on the Saleae Pro 16, but have done. Its sometimes useful to check the analog levels going into an ADC on a microcontroller. Its not a oscilloscope replacement, but it saves turning the scope (or even a multimeter) on to just verify something when you already have the thing out and hooked up to a board. Its also extremely portable.
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In my opinion an Oscilloscope and a Logic Analyser are very different tools with different usage.
I completely agree with this. I use my Saleae more than my scope and that is saying a lot because my scope sits on a table right next to me.
Their pro 8 or pro 16 at 500MSa/s would have 10 samples per clock for 50 MHz SPI and 4 samples per clock for 125 MHz SPI.
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I find the hacked Rigol 1054Z very compelling. However, decoding SPI on this scope is limited to 25 MHz.
I don't know about the analogue channels, but the MSO1000Z LA channels will decode 50MHz SPI, down to a 250MHz sample rate.
Edit: I just tried it on the analogue channels, and while the signals ain't pretty, it does decode fine on a 50MHz SPI stream.
That's interesting because in theory the 1000Z is only rated for 25 MHz at 250 Sa/s when using 3 or 4 analog channels since it's all going through a single chip. I suppose even with attenuation the signal is enough to trigger the decoder, is the 1000Z decoding trigger adjustable? Someone stated that the 1000Z can do 150 MHz before it hits -3db attenuation:
https://www.eevblog.com/forum/testgear/new-rigol-ds1054z-oscilloscope/msg524797/#msg524797 (https://www.eevblog.com/forum/testgear/new-rigol-ds1054z-oscilloscope/msg524797/#msg524797)
1000Z Bandwidth:
Frequency Amplitude
10 MHz 0.0 dBm
100 MHz -1.5 dBm
150 MHz -3.0 dBm
393 MHz -10.0 dBm
447 MHz -20.0 dBm
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Their pro 8 or pro 16 at 500MSa/s would have 10 samples per clock for 50 MHz SPI and 4 samples per clock for 125 MHz SPI.
According to the datasheet the Saleae Pro 8/16 are only capable of 500 MS/s on 4 channels, when using more than 4 channels it drops down to 100 MS/s. That's only 1 sample per clock at 100 MHz.
http://downloads.saleae.com/specs/Logic+Pro+16+Data+Sheet.pdf (http://downloads.saleae.com/specs/Logic+Pro+16+Data+Sheet.pdf)
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USBee went out of business yesterday: http://www.usbee.com/company.htm (http://www.usbee.com/company.htm)
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Can the DS4014 be hacked to 500 MHz? I was reading in the scope sizing guides that the analog bandwidth should be around 10 times the frequency you want to measure if you want an accurate waveform due to the rise times of square waves and such. It's becoming apparent to me that a 100 MHz scope is nothing but a toy when it comes to computer engineering applications, what do I need to really get into the game? I'd prefer not getting nickeled and dimed buying toy equipment that is ultimately useless for the task at hand.
My quest is to build a i486 based system from scratch. Linux dropped support for the i386, so I see the i486 as the oldest representation of the modern x86 architecture.
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I don't like the USB logic analysers because either the memory is short or the sample rate low.
Nico, you left out: or the software sucks. ;)
On the first 2 counts, I find Hantek's 4032L more than adequate (64M sample depth, 32 channels wide; at up to 400M samples/sec). It also has a good front-end for handling logic levels. It's on the 3rd count that it falls short.
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nbritton the answer to your question is yes.
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Their pro 8 or pro 16 at 500MSa/s would have 10 samples per clock for 50 MHz SPI and 4 samples per clock for 125 MHz SPI.
According to the datasheet the Saleae Pro 8/16 are only capable of 500 MS/s on 4 channels, when using more than 4 channels it drops down to 100 MS/s. That's only 1 sample per clock at 100 MHz.
Only 4 channels are needed for SPI. And only 4 samples per clock will definitely decode SPI, though it won't give you very precise bit transitions.
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It's becoming apparent to me that a 100 MHz scope is nothing but a toy when it comes to computer engineering applications...
That's certainly not a true statement, in general.
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I don't like the USB logic analysers because either the memory is short or the sample rate low.
Nico, you left out: or the software sucks. ;)
I should note that I don't have a Windows PC. As a matter of principle I avoid Microsoft products because I make my living off of Linux and UNIX. So that leaves Mac or Linux as the host operating system for a USB LA.
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It's becoming apparent to me that a 100 MHz scope is nothing but a toy when it comes to computer engineering applications...
That's certainly not a true statement, in general.
How so, can you articulate on that? Pretty much everything I see in the computer space is running in the gigahertz range. Even the Arduino is running at 15 MHz, the scope sizing guidelines recommend 10x the bandwidth, so you would need a 150 MHz scope for this.
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Since you don't need to measure anything that is connected to the CPU directly (like in the old days) you only deal with peripherals and these run much slower. In many cases you can slow the peripherals (I2C, SPI, etc) down too to make signals measurable if necessary.
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It's becoming apparent to me that a 100 MHz scope is nothing but a toy when it comes to computer engineering applications...
That's certainly not a true statement, in general.
How so, can you articulate on that? Pretty much everything I see in the computer space is running in the gigahertz range. Even the Arduino is running at 15 MHz, the scope sizing guidelines recommend 10x the bandwidth, so you would need a 150 MHz scope for this.
It's a case of using a rule of thumb, but rejecting that experience and analytical skills can work in your favour.
I'd have no problem in using a 1Gsa/s 500MHz bw scope to figure out if a 200MHz clock signal exists. However the signal won't look great even if I use reasonable probing techniques (i.e. probes that cost more than a DS1054Z, or use a homebrew 10:1 50 ohm resistive)
If you want to probe at GHz speeds on the board you will still need to know about the effects your probes will have, even though you may have spent $10k or $20k just on the probe, before you even bought the scope.
Designing, prototyping and testing PC motherboards at bus speed level is not the domain of the DS1054Z, or, in fact, the domain of 99%+ of the oscilloscopes on the planet, so most of the work is done in software before the first board is even fabricated.
As nctnico says, in embedded systems by far most of what you need to know and that's exposed isn't GHz. When it is, the scope's the least of your problems, it's figuring out how to probe it.
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Since you don't need to measure anything that is connected to the CPU directly (like in the old days) you only deal with peripherals and these run much slower. In many cases you can slow the peripherals (I2C, SPI, etc) down too to make signals measurable if necessary.
I understand that. However, one of the things I would like to do is build a computer (perferably x86 architecture) from scratch, i.e. selecting and laying out the components onto a PCB. Lets use a 486DX4 100 MHz as an example, the front side bus on this runs at 33.3 MHz. According to scope sizing guides I would need a 333 MHz scope to accurately represent a 33.3 MHz square wave due to waveform rise times. Furthermore, the PCI bus is 32-bit and also the 72-pin SIMM is 32-bit, so wouldn't this mean I need a 32 channel logic analyzer?
Am I being realistic here with my goals and requirements?
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It's becoming apparent to me that a 100 MHz scope is nothing but a toy when it comes to computer engineering applications...
That's certainly not a true statement, in general.
Signals don''t vanish above the rated bandwidth, they just attenuate (get smaller). This affects harmonics and changes the shapes of things. If you know signal theory and practice a bit then you can compensate in your head (up to a point).
eg. A DS1054Z will show a 50MHz square wave with 'ringing' artifacts. Those artifacts aren't coming from your PCB, they're there because the third harmonic isn't coming through loud and clear.
Knowing how to probe? That's a whole other layer of learning. The overshoots on your rising edges? Probably the way you connected the probe. A more expensive oscilloscope won't save you from knowing that.
Bottom line: Even the most expensive oscilloscaope won't just show you the beautiful waveforms you might be imagining when you arrive from a purely digital world. It takes knowledge and practice.
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It's becoming apparent to me that a 100 MHz scope is nothing but a toy when it comes to computer engineering applications...
That's certainly not a true statement, in general.
Signals don''t vanish above the rated bandwidth, they just attenuate (get smaller). This affects harmonics and changes the shapes of things. If you know signal theory and practice a bit then you can compensate in your head (up to a point).
Knowing how to probe? That's a whole other layer of learning. The overshoots on your rising edges? Probably the way you connected the probe. A more expensive oscilloscope won't save you from knowing that.
Bottom line: Even the most expensive oscilloscaope won't just show you the beautiful waveforms you might be imagining when you arrive from a purely digital world. It takes knowledge and practice.
As Howard points out: $$$$ probes
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You can probably design and build the whole thing without measuring any hardware at all. After its built (and if it's not working) you might need to measure some clock lines, to verify they are actually clocking, but I very much doubt you need to measure anything on a 32bit wide memory bus. Again you might probe a line or two to ensure it looks ok. Because your hardware will be fairly expensive to build, you would be wise to invest time in setting up software simulations to ensure theoretical signal integrity of your board design. A basic 100mhz scope will be fast enough to indicate if a 33mhz clock line is working or not. I'd say it would be a fairly ambitious project if you don't have a heap of pcb layout experience.
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Since you don't need to measure anything that is connected to the CPU directly (like in the old days) you only deal with peripherals and these run much slower. In many cases you can slow the peripherals (I2C, SPI, etc) down too to make signals measurable if necessary.
I understand that. However, one of the things I would like to do is build a computer (perferably x86 architecture) from scratch, i.e. selecting and laying out the components onto a PCB. Lets use a 486DX4 100 MHz as an example, the front side bus on this runs at 33.3 MHz. According to scope sizing guides I would need a 333 MHz scope to accurately represent a 33.3 MHz square wave due to waveform rise times. Furthermore, the PCI bus is 32-bit and also the 72-pin SIMM is 32-bit, so wouldn't this mean I need a 32 channel logic analyzer?
Am I being realistic here with my goals and requirements?
I think there's confusing of Bandwidth of the scope versus it's Sampling Rate. a 100Mhz Bandwidth scope can show that square wave just fine regardless if its a analog or a dso type and for an analog scope that's the end of the question,
For a DSO you now have to bring in the sampling rate. This is why the DS1000Z series have 1Ghz sampling for 100Mhz. That is of course for 1 channel, at 2 ch it's 500Mhz sampling and all 4 is 250Mhz per channel for the sampling rate.
if you use all 4 channels for a SPI bus then you have 100Mhz Bandwidth but 250Mhz sampling rate per channel. Can it do what you're talking about I say yes, would a higher sample rate DSO do better sure. But the DS1000z can do it. Also keep in mind, do you really need to look at CS, CLK, MISO and MOSI. if you just look at CLK and MISO for example you have 500Mhz sample rate. again is it idea, no but you can do it.
And as has been said, for Bandwidth, that is the specified -3db point not the end of life of the scope. with care you can go past it.
I feed in a 500Mhz signal in the mso1000z I have and at 1vpp in i still saw it but at <100mV (dont' remember the actual value) but it was there.
also, my MSO1000z I measured the bandwidth at 148Mhz by measuring the -3db point
That my 2 cents FWIW.
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I'd be pretty unfazed (see what I did there) about using a 100MHz BW 250Msa/s per ch scope on a 33MHz bus.
Remember that a lot of what you're seeing isn't 33MHz, maximum data change rate on worst case is half that.
For things like RAS and CAS, you're looking at relative timing and phase differences, and for set up and hold times etc, 250Msa/s may just about cut it, if not go up to 500Msa/s per ch by only using 2ch and work from there.
Back in the days of the 33MHz bus CPU, in the early 90s, there were pretty much no DSOs that would accomplish single shot 1Gsa/s, but I stand to be corrected of course.
Edit: Changed some GSa/s to MSa/s due to operator error.
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I'd be pretty unfazed (see what I did there) about using a 100MHz BW 250Gsa/s per ch scope on a 33MHz bus.
Remember that a lot of what you're seeing isn't 33MHz, maximum data change rate on worst case is half that.
For things like RAS and CAS, you're looking at relative timing and phase differences, and for set up and hold times etc, 250Gsa/s may just about cut it, if not go up to 500Gsa/s per ch by only using 2ch and work from there.
I guess you mean MSa/s, not GSa/s.
Back in the days of the 33MHz bus CPU, in the early 90s, there were pretty much no DSOs that would accomplish single shot 1Gsa/s, but I stand to be corrected of course.
That's wrong, there were actually quite a few scopes that could do single shot 1GSa/s the early '90s, for example the HP 54510A (my work horse back then).
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One thing to also consider when looking at scopes is how the sample rate goes down with the number of enabled channels.
DS1054Z - 1ch=1GSa/s, 2ch=500MSa/s, 4ch=250MSa/s.
DS2072 - 1ch=2GSa/s, 2ch/1GSa/s
DS4014 - 1ch=4GSa/s, 2ch=4GSa/s (CH1 + CH3), 4ch=2GSa/s
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Some shots I took a few hours ago on an MSO1074Z decoding SPI at 50MHz, one with LA at 1Gsa/s (it still works at 250Msa/s) and the other on analogue channels a 250Msa/s... (which, by the way I can't currently seem to get to decode on an Agilent/Keysight MSO7104B 1GHz/4GSa/s scope which appears to give up beyond 35MHz for SPI on my unit, errors of operator excepted and accepted of course).
Edit: probing on analogue channels is with stock probe end clips and crocodile ground leads attached close by: I don't necessarily recommend that at these speeds, but that's what worked unexpectedly consistently well on this occasion.
(http://i34.photobucket.com/albums/d123/photobucket391/NewFile1_zpsfrxdxbhw.png) (http://s34.photobucket.com/user/photobucket391/media/NewFile1_zpsfrxdxbhw.png.html)
(http://i34.photobucket.com/albums/d123/photobucket391/DS1Z_QuickPrint1_zpsembbmviq.png) (http://s34.photobucket.com/user/photobucket391/media/DS1Z_QuickPrint1_zpsembbmviq.png.html)
Note that triggering on the Rigol in SPI seems not so good in SPI. Couldn't get that to work, I think I covered this in another thread a month or so ago.
Edit II: changed GSa/s to MSa/s, due to operator having a Saturday night brain fart.
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I'd be pretty unfazed (see what I did there) about using a 100MHz BW 250Gsa/s per ch scope on a 33MHz bus.
Remember that a lot of what you're seeing isn't 33MHz, maximum data change rate on worst case is half that.
For things like RAS and CAS, you're looking at relative timing and phase differences, and for set up and hold times etc, 250Gsa/s may just about cut it, if not go up to 500Gsa/s per ch by only using 2ch and work from there.
I guess you mean MSa/s, not GSa/s.
Not necessarily, iff you are looking at timing differences in repetitive signals using equivalent time sampling rather than real-time one-shot sampling.
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I'd be pretty unfazed (see what I did there) about using a 100MHz BW 250Gsa/s per ch scope on a 33MHz bus.
Remember that a lot of what you're seeing isn't 33MHz, maximum data change rate on worst case is half that.
For things like RAS and CAS, you're looking at relative timing and phase differences, and for set up and hold times etc, 250Gsa/s may just about cut it, if not go up to 500Gsa/s per ch by only using 2ch and work from there.
I guess you mean MSa/s, not GSa/s.
Indeed, my error.
Back in the days of the 33MHz bus CPU, in the early 90s, there were pretty much no DSOs that would accomplish single shot 1Gsa/s, but I stand to be corrected of course.
That's wrong, there were actually quite a few scopes that could do single shot 1GSa/s the early '90s, for example the HP 54510A (my work horse back then).
I didn't realise that was single shot, I assumed it must've been equivalent time. That must've been quite something back then. I'd jumped ship and was software guy in the late 80s & 90s so I'll hold my hands up and accept your superior knowledge. Did anyone else do that calibre of DSO in single shot at that time?
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Tektronix had the TDS600 series realtime scopes in that era going up to several Gs/s IIRC.
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Signals don''t vanish above the rated bandwidth, they just attenuate (get smaller). This affects harmonics and changes the shapes of things. If you know signal theory and practice a bit then you can compensate in your head (up to a point).
I don't know signal theory. I don't know pcb layout. The extent of my experience is I dabbled in analog electronics in high school and aced college level circuit analysis. I haven't done electronics in over a decade. I have a renewed interest in this, as a hobby, because I'm now living in a small apartment in a big city that is expensive to live in. I need a hobby that doesn't take up a lot of space, I also need a hobby that is connected in some way to my profession as a Linux system engineer. I find programming semi-boring, I've always been drawn to hardware. Perhaps I'm being too ambitious, what is realistic for someone who is a novice amateur? Money is not the most highest concern for me, I'm more interested in buying the right tools for the job. The only scope I've owned is a Tektronix 2213.
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You can probably design and build the whole thing without measuring any hardware at all. After its built (and if it's not working) you might need to measure some clock lines, to verify they are actually clocking, but I very much doubt you need to measure anything on a 32bit wide memory bus. Again you might probe a line or two to ensure it looks ok. Because your hardware will be fairly expensive to build, you would be wise to invest time in setting up software simulations to ensure theoretical signal integrity of your board design. A basic 100mhz scope will be fast enough to indicate if a 33mhz clock line is working or not. I'd say it would be a fairly ambitious project if you don't have a heap of pcb layout experience.
Then what do I need a scope for? Wouldn't I be just as well off with frequency counter? Seriously, if I don't need to care about what the waveform looks like why do I need a scope?
Edit: Also what am I learning here? My goal in building a computer from scratch isn't to learn pcb layout, it is to gain a deeper understanding of how a computer operates so that I can apply that knowledge to my job as a Linux system engineer.
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You can probably design and build the whole thing without measuring any hardware at all. After its built (and if it's not working) you might need to measure some clock lines, to verify they are actually clocking, but I very much doubt you need to measure anything on a 32bit wide memory bus. Again you might probe a line or two to ensure it looks ok. Because your hardware will be fairly expensive to build, you would be wise to invest time in setting up software simulations to ensure theoretical signal integrity of your board design. A basic 100mhz scope will be fast enough to indicate if a 33mhz clock line is working or not. I'd say it would be a fairly ambitious project if you don't have a heap of pcb layout experience.
Then what do I need a scope for? Wouldn't I be just as well off with frequency counter? Seriously, if I don't need to care about what the waveform looks like why do I need a scope?
Edit: Also what am I learning here? My goal in building a computer from scratch isn't to learn pcb layout, it is to gain a deeper understanding of how a computer operates so that I can apply that knowledge to my job as a Linux system engineer.
The more you say about your goals, the more we can avoid spending our time making suggestions that you find irrelevant.
Have a look at the arduino ecosystem, and pick a project to do with an arduino plus shields plus your custom hardware.
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I'm getting that idea as well. An Arduino or Raspberry Pi will be much more rewarding than tinkering with obsolete hardware. The same baic principles still apply though.
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I'm getting that idea as well. An Arduino or Raspberry Pi will be much more rewarding than tinkering with obsolete hardware. The same baic principles still apply though.
The arduino has the advantage (for the OP) of being much simpler and closer to bare-silicon. There's no operating system in the way. The bootloader loads the program and gets out of the way - much like MSDOS :)
The RPi is much more "powerful" because it is linux based (which may be a disadvantage for the OP) - but also much more complex.
Either will have the advantage (compared with building an i486) that the OP can quickly use them to do something, rather than just exist.
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Then what do I need a scope for? Wouldn't I be just as well off with frequency counter? Seriously, if I don't need to care about what the waveform looks like why do I need a scope?
Edit: Also what am I learning here? My goal in building a computer from scratch isn't to learn pcb layout, it is to gain a deeper understanding of how a computer operates so that I can apply that knowledge to my job as a Linux system engineer.
I would suggest perhaps the most challenging part of building a computer from scratch is going to be the board layout. Don't underestimate the importance the board design plays on high speed signals, its not just about ensuring pins are connected to each other. You will then need the scope to see that the signals are present, correct and signal integrity is there.
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I've played with the arduino and raspberry pi and I didn't find them very challenging, with these devices it largely came down to programming and that's not really what I'm interested in learning. What I want to learn are things like how digital electronics work, how a CPU works, how memory works, how to interface with memory and perform operations on the bits stored in it, how buses work and how data is transferred around the system, how you assemble bits into higher ordered data structures, how to program in machine code and assembly language, how bootloaders work, and last but not least why operating systems are designed the way they are. Basically I want to learn in great detail how you get from electrons to a functional computer.
Edit: I'm more interested in the architecture then anything else, that's why I initially said I would like to build a 1970s era computer. Computers from this era still had discrete components. Thinking about it more, I think the first step would be to build a simplistic microcontroller from discrete components. This would help me learn things like gates, digital logic, adders, ALUs, microcode, etc. Does anyone know of a training kit that has all of this? I think a lot of this could be done in simulation or on a FPGA today, however, I want to be able to touch it. I learn best through hands on labs.
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So don't use the boatloader or built in OS on an Arduino. Erase it and start from scratch. If you want to write your own OS and or kernel in assembler that last thing your going to want is to do it on unproven hardware.
Arduino is a relativly simple microcontroller and if you program it in assembler it will be about as close as you can get to the silicon, but is still actually achievable. You'll no doubt get frustrated and turn to C fairly quickly, but even in C you will still be required to manipulate registers in bits and bytes, and will certainly teach you how the guts of it work when it's not handed to you on a plate by an off the self OS.
I still write some things in assembler now and then, if nothing else it's good to understand what C compiler is building.
If that's all still to easy, you could probably do the same with a 486 board I guess, erase the bios and let the fun begin.
You will still want a scope so you can verify that your bit/byte manipulation is having the desired effect on the IO line of the chip, but for the purposes of learning this stuff, any scope will do the job.
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So don't use the boatloader or built in OS. Erase it and start from scratch. If you want to write your own OS and or kernel in assembler that last thing your going to want is to do it on unproven hardware.
You could do the same with a 486 board, buy an old board, erase the bios and let the fun begin.
Removing the BIOS and firmware is a great idea. However, I don't know how to program an eeprom, or write machine code, or know what kind of microcode to write. We need to back up several steps.
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You will still want a scope so you can verify that your bit/byte manipulation is having the desired effect on the IO line of the chip, but for the purposes of learning this stuff, any scope will do the job.
Yes I'm coming back around, full circle, to the conclusion that any scope will work for what I want to do. However, I'm still on the fence if I should get an MSO, or a DSO + LA, or an MSO + discrete LA, or just a combo USB DSO/LA. When I woke up this morning I was heavy leaning towards an MSO2072A. Also I'm still on the fence whether the 2072A is a better value than the 1054Z, on paper the 2072A offers over double the spec:
300 MHz vs 100 MHz
2G Sa/s vs 1G Sa/s
56 Mpts vs 24 Mpts
500uV vs 1mV
Furthermore it has true segmented memory, statistical analysis, et. al., whereas these type of features appear to be cobbled together as an afterthought on the 1054Z. I really hate working with dodgy and poorly thought out systems because at the end of the day they just end up frustrating me; my peace of mind is worth a lot to me.
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on paper the 2072A offers over double the spec:
at 3x the price - does not seen equal
If 2x the price I would say the odds are even
I just don't get it when someone compares a $400 scope with a $1200 one ??
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I'm getting that idea as well. An Arduino or Raspberry Pi will be much more rewarding than tinkering with obsolete hardware. The same baic principles still apply though.
Yes. Building a 486DX PC seems (a) Very ambitious and (b) Totally pointless. You'll be living alone on an island.
If I was going to build a computer these days I'd go for an ARM chip. If I just wanted to tinker with hardware and learn electronics I'd use Arduino.
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Starting to get somewhere. You won't need anything at the point your starting. I suggest, get a Microchip PIC EXPLORER 16 board and a PICKIT3. Start by programming it, in assembler, to flash an LED. (no really thats harder than you think, you need to do a lot of configuration to just achieve something as seemingly simple as flash a led). Next write some code to use the Analog to digital converter to sample the pot and display the result on the LEDs. Then start displaying some Text on the LCD. You'll now be into I2C buses and IO port expanders...nice useful stuff and you might even need a scope to figure out why the I2C bus isn't working for you.
You really don't need an oscilloscope for any of this...and if you don't know anything about bit manipulation or writing assembler it will keep you busy for ages. Thats why Arduino's are so popular...its all done for you and makes it seem trivial but its really not as easy as you might be thinking/expecting.
If you just want to buy some tools/toys now (and there is nothing wrong with that :) ) buy a 100Mhz 4 channel scope (whatever model that is), don't buy any extra decoding stuff, learning to decode the bit streams on a bus will do you good and sounds like part of what you want to learn., You can add decoding licences later (or hack them on if thats your thing) Some scopes let you have the LA activated by software too (they send you the adapters and probes), so you can add it later if you need it so maybe look for models with lots of software upgrade options.
IMO 100Mhz is more than enough for 99% of what your likely to encounter/need, and with 4ch you can debug most things.
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I've played with the arduino and raspberry pi and I didn't find them very challenging, with these devices it largely came down to programming and that's not really what I'm interested in learning. What I want to learn are things like how digital electronics work, how a CPU works, how memory works, how to interface with memory and perform operations on the bits stored in it, how buses work and how data is transferred around the system, how you assemble bits into higher ordered data structures, how to program in machine code and assembly language, how bootloaders work, and last but not least why operating systems are designed the way they are. Basically I want to learn in great detail how you get from electrons to a functional computer.
That sounds great; I wish more people had that understanding.
You could get a good understanding of most of those by starting at the atmega328 chip level and initialising all the hardware yourself. Get an Atmel AVR Dragon, which will allow you to program and debug atmega328 devices on their own and in whatever board and system you design.
You need to pick a suitable project, one which is within your scope but will stretch your capabilities. An example of that would be that recently I wanted to make a date/time/pill reminder for my parents that would run for months on a set of small batteries. Arduinos would have used too much power, so I started with the atmega328, programmed it in the Dragon, and then designed and constructed the board containing the MCU, battery and peripherals (switches and an LCD display).
That is a suitable level for a hardware beginner - even with something that simple you will find that you will have a lot to learn and will make many mistakes. A 100MHz scope will be very valuable - but not necessary;I didn't have one.
Be aware that, if you want to avoid subtle intermittent failures, you are going to have to learn about ground planes, decoupling, ground bounce, probing techniques and limitations, inductance, different types of capacitor, time<->frequency relationship, transmission lines, and many other topics. Those will be tractable for a beginner with a 100MHz scope if you use arduino class MCUs such as the the atmega328. If you try to build a 486 class machine from scratch, you will almost certainly have significant problems.
(If you use solderless breadboards, be prepared to spend as much time debugging the breadboard as debugging your circuit. Reason: their general frailty plus electrical characteristics inherent in their design)
Edit: I'm more interested in the architecture then anything else, that's why I initially said I would like to build a 1970s era computer. Computers from this era still had discrete components. Thinking about it more, I think the first step would be to build a simplistic microcontroller from discrete components. This would help me learn things like gates, digital logic, adders, ALUs, microcode, etc. Does anyone know of a training kit that has all of this? I think a lot of this could be done in simulation or on a FPGA today, however, I want to be able to touch it. I learn best through hands on labs.
If you had been around 30-40 years ago, you would have loved bit slice processors such as the AMD2900 or Intel 3000 families.
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If you had been around 30-40 years ago, you would have loved bit slice processors such as the AMD2900 or Intel 3000 families.
You might also be interested in the "weeny bitter", see http://www.smrcc.org.uk/members/g4ugm/acc.htm (http://www.smrcc.org.uk/members/g4ugm/acc.htm) August 75 and following.
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I'd be pretty unfazed (see what I did there) about using a 100MHz BW 250Gsa/s per ch scope on a 33MHz bus.
Remember that a lot of what you're seeing isn't 33MHz, maximum data change rate on worst case is half that.
For things like RAS and CAS, you're looking at relative timing and phase differences, and for set up and hold times etc, 250Gsa/s may just about cut it, if not go up to 500Gsa/s per ch by only using 2ch and work from there.
I guess you mean MSa/s, not GSa/s.
Not necessarily, iff you are looking at timing differences in repetitive signals using equivalent time sampling rather than real-time one-shot sampling.
Show me a scope that does 250GSa/s or 500GSa/s ETS. Even modern scopes don't go beyond 200GSa/s for ETS, and upper high end scopes with 100+ GSa/s real-time sample rate usually don't do ETS at all any more.
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That's wrong, there were actually quite a few scopes that could do single shot 1GSa/s the early '90s, for example the HP 54510A (my work horse back then).
I didn't realise that was single shot, I assumed it must've been equivalent time. That must've been quite something back then.
Well, such high sample rates weren't as common as they are today but it wasn't particularly exceptional (the 54500 Series was HP's mid-range scope series). There also was the older 54111D (1GSa/s with two channels or 2GSa/s on a single channel; came out in 1989).
Tektronix had some 1GSa/s real-time scopes at that time.
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I've played with the arduino and raspberry pi and I didn't find them very challenging, with these devices it largely came down to programming and that's not really what I'm interested in learning. What I want to learn are things like how digital electronics work, how a CPU works, how memory works, how to interface with memory and perform operations on the bits stored in it, how buses work and how data is transferred around the system, how you assemble bits into higher ordered data structures, how to program in machine code and assembly language, how bootloaders work, and last but not least why operating systems are designed the way they are. Basically I want to learn in great detail how you get from electrons to a functional computer.
If that is your goal you better start with a Z80 or something like that. These are easy to use (no weird cycle or clock signals like on the Motorola cpus).
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Thinking about it more, I think the first step would be to build a simplistic microcontroller from discrete components. This would help me learn things like gates, digital logic, adders, ALUs, microcode, etc. Does anyone know of a training kit that has all of this? I think a lot of this could be done in simulation or on a FPGA today, however, I want to be able to touch it. I learn best through hands on labs.
Get yourself a load of 74LS chips and a few dozen mini breadboards (http://www.ebay.com/sch/i.html?_nkw=mini+breadboard). Build an Apple II (or whatever).
I would build something simple at about 1MHz clock speed that actually has software and schematics for hardware hints.
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Edit: I'm more interested in the architecture then anything else, that's why I initially said I would like to build a 1970s era computer. Computers from this era still had discrete components. Thinking about it more, I think the first step would be to build a simplistic microcontroller from discrete components. This would help me learn things like gates, digital logic, adders, ALUs, microcode, etc. Does anyone know of a training kit that has all of this? I think a lot of this could be done in simulation or on a FPGA today, however, I want to be able to touch it. I learn best through hands on labs.
Sounds good. My recommendation then would be to forget about Raspberry Pis, ATMegas and other modern day complex stuff and start with something simple like an 8051. Yes, it's old but the 8051 is cheap, slow (means you don't need high speed instruments to look at your signals) and simple, and a perfect starting point if you want to learn how computers work. There are various 8051 kits around but you could as well build your own, which is much easier than doing the same with much more complex and faster processors like an intel 486 or one of the modern complex micrcontrollers. Plus rolling your own board layout is much easier as the timing is a lot more forgiving.
Disclosure: the 8051 was how I learned about computers back in the days when those things were pretty standard microcontrollers for many applications. And yes, right now I'm feeling old ;)
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That's wrong, there were actually quite a few scopes that could do single shot 1GSa/s the early '90s, for example the HP 54510A (my work horse back then).
I didn't realise that was single shot, I assumed it must've been equivalent time. That must've been quite something back then.
Well, such high sample rates weren't as common as they are today but it wasn't particularly exceptional (the 54500 Series was HP's mid-range scope series). There also was the older 54111D (1GSa/s with two channels or 2GSa/s on a single channel; came out in 1989).
Tektronix had some 1GSa/s real-time scopes at that time.
I think people tend to look at what they can buy off the shelf, and assume that is the current state of the art. What you can buy as a standard part is largely determined by there being a big enough market, willing to pay a high RE, to justify the NRE and marketing costs of launching the thing. Instrument makers are usually well ahead of people like Analog Devices and TI in the highest speed ADCs, because they are basically the only market for these things, and they can justify the entire life cycle costs of developing them. It took DSPs and FPGAs fast enough to crunch through the output of a 1Gsps converter before the incentive to make off the shelf ones was there.
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Disclosure: the 8051 was how I learned about computers back in the days when those things were pretty standard microcontrollers for many applications. And yes, right now I'm feeling old ;)
If the 8051 was around when you started, then you either started late in life, or you are not that old. :-)
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I'm not a fan of the 8051 because it has way too many weird things. Programming it in C also means keeping a lot of the 8051 limitations in mind during programming. Better use a real CPU with a normal data + address bus, real stack, etc.
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I think people tend to look at what they can buy off the shelf, and assume that is the current state of the art. What you can buy as a standard part is largely determined by there being a big enough market, willing to pay a high RE, to justify the NRE and marketing costs of launching the thing. Instrument makers are usually well ahead of people like Analog Devices and TI in the highest speed ADCs, because they are basically the only market for these things, and they can justify the entire life cycle costs of developing them. It took DSPs and FPGAs fast enough to crunch through the output of a 1Gsps converter before the incentive to make off the shelf ones was there.
You're absolutely right, it's T&M manufacturers who drive ADC development for their scopes and signal analyzers, and who invest a lot of money in pushing them further. Mass market component manufacturers like AD or TI don't, they're only interested in large volumes, and therefore what they're offering is mostly standard tech and not state of the art.
I mean, what's the fastest 8bit ADC you can get on the component market these days, 4GSa/s or something like that? In scopes we're currently at 240GSa/s.
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Disclosure: the 8051 was how I learned about computers back in the days when those things were pretty standard microcontrollers for many applications. And yes, right now I'm feeling old ;)
If the 8051 was around when you started, then you either started late in life, or you are not that old. :-)
When I started the thing was actually called MCS51. Later we went to the 8085. So maybe I'm not that old after all (although much closer to retirement than to graduation) :)
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I'm not a fan of the 8051 because it has way too many weird things. Programming it in C also means keeping a lot of the 8051 limitations in mind during programming. Better use a real CPU with a normal data + address bus, real stack, etc.
Well, I wouldn't suggest to program an 8051 in a High Level Language like C, which just adds unnecessary complexity itself. And if the aim was to built a computer to run C programs then I'd agree. But don't forget that the OP wants to learn about the internal workings of computers, and a low complexity microcontroller programmed in Assembler is much easier than to use a complex CPU, add all the glue logic like memory controller to it, and then run interpreted or compiled programs on it.
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A Z80 isn't difficult to use. This is a Z80 board I made over 20 years ago:
(https://www.eevblog.com/forum/testgear/best-entry-level-oscilloscope-for-computer-engineering/?action=dlattach;attach=170983;image)
At that time I only had a 20MHz ananalog scope and a multimeter to get it working. This was also the first PCB design I made using a CAD package; I know the component placement is far from optimal. I actually placed the Z80 between the RAM and the EPROM not realising the RAM and EPROM have almost identical connections so routing would have been much easier.
It only takes a decoder like the 74x138 and some OR gates (74x32) to decode the read/write strobes for the memory. The Z80 has a seperate I/O bus so an extra decoder allows to create more I/O space (which is where the extra chips and headers on the board are for).
Connecting an 8051 to external memory takes the same amount of glue logic and much more assembly programming to access that external memory! The Z80 really is the simplest choice here.
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A Z80 isn't difficult to use.
Yes, the Z80 could be a good alternative (I thought you meant newer/more complex CPUs).
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Another vote for the Z80 if you want to know about busses at what not.
Although it wasn't the first hand wired computer I built, my first Z80 was hand wired on stripboard in the 70s, and I got it working without a scope, just an LED plus resistor as a logic probe and a crap 1k ohm per volt multimeter were all I had as test equipment. Occasionally I might use a monostable and LED to show if something was oscillating or not if the pulse was so narrow it couldn't be discerned visually on an LED from always on or always off, but usually an LED plus resistor was all you needed.
True, I wouldn't want to do it that way nowadays, but TE was in relative terms really very expensive. Occasionally I'd have access to a scope, but it was rare. I remember the first scope I used with a delayed timebase, that really was something when trying to dubug your code at bus level, which is what we did back in those days without debuggers, logic analysers or in circuit emulators. When initially getting a machine up for the first time, we used to set a trigger reference point, and go through each of the control, data and address bus bits one at a time and mark down the binary on paper. You could then see the machine code and where things weren't happening as expected.
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Another vote for the Z80 if you want to know about busses at what not.
Although it wasn't the first hand wired computer I built, my first Z80 was hand wired on stripboard in the 70s, and I got it working without a scope, just an LED plus resistor as a logic probe and a crap 1k ohm per volt multimeter were all I had as test equipment. Occasionally I might use a monostable and LED to show if something was oscillating or not if the pulse was so narrow it couldn't be discerned visually on an LED from always on or always off, but usually an LED plus resistor was all you needed.
True, I wouldn't want to do it that way nowadays, but TE was in relative terms really very expensive. Occasionally I'd have access to a scope, but it was rare. I remember the first scope I used with a delayed timebase, that really was something when trying to dubug your code at bus level, which is what we did back in those days without debuggers, logic analysers or in circuit emulators. When initially getting a machine up for the first time, we used to set a trigger reference point, and go through each of the control, data and address bus bits one at a time and mark down the binary on paper. You could then see the machine code and where things weren't happening as expected.
Just so, except I used a 6800 and avoided stripboard in favour of homebrew PCBs made with bizarre etch resists :)
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I did similar with a Z80 in the 70s. I did however have a home built copy of a 10 Mhz Telequipment Transistorized scope to use. I made my own hand drawn PCBs for the Z80 system. Main problem I had was forgetting I had inverted the enable signal on the separate Dynamic ram board and inverting it elsewhere as well to feed that board. It worked some of the time in that mode but was very unreliable and tended to forget everything in the RAM! Programming was all in a 1K 2708 UVROM in machine code. Later development moved on to Tiny Basic and Forth. Certainly an easier chip to run with as it has it's own clock and single rail use.
John
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Indeed, back in those days it was common to need to supply multiple supply rails and multi-phase clocks, often at non-TTL levels, which complicated things. The Z80 largely simplified all that. However, getting the integrated dynamic RAM interface to work in spec with the DRAM of the day was another piece of work altogether. RC and gate propagation delays seemed to be the order of the day to get the timings just right.
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on paper the 2072A offers over double the spec:
at 3x the price - does not seen equal
If 2x the price I would say the odds are even
I just don't get it when someone compares a $400 scope with a $1200 one ??
The DS2072A is not $1,200, it is $789 over at tequipment.net with the eevblog discount, the price difference compared to the DS1054Z is $414.
DS1054Z: $375
MSO1074Z: $785
MSO Option = $410
DS2072A: $789
MSO2072A: $1,165
MSO Option = $376
From what I hear the MSO option on the DS1054Z is worthless, so you would need to buy a DS1054Z plus a separate logic analyzer. The Saleae Logic Pro 16 costs $599. Now you're up to $974. For $191 more you can upgrade to the MSO2072A.
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Sounds good. My recommendation then would be to forget about Raspberry Pis, ATMegas and other modern day complex stuff and start with something simple like an 8051.
Nah, I wouldn't user an 8051. It has built in memory, etc. If you're doing that then you might as well use something current like an AVR chip. Putting an AVR chip on a breadboard isn't much of a challenge though (plug it in, power it up, load a program - they just work!)
If I wanted to build a small computer with external buses I'd go for a Z80 or 6502. They need external RAM, ROM, I/O chips, etc.
Frequencies in the 1-4MHz range also don't need carefully designed PCBs to make them work. You can use perfboard and bits of wire.
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on paper the 2072A offers over double the spec:
at 3x the price - does not seen equal
If 2x the price I would say the odds are even
I just don't get it when someone compares a $400 scope with a $1200 one ??
The DS2072A is not $1,200, it is $789 over at tequipment.net with the eevblog discount, the price difference compared to the DS1054Z is $414.
DS1054Z: $375
MSO1074Z: $785
MSO Option = $410
DS2072A: $789
MSO2072A: $1,165
MSO Option = $376
From what I hear the MSO option on the DS1054Z is worthless, so you would need to buy a DS1054Z plus a separate logic analyzer. The Saleae Logic Pro 16 costs $599. Now you're up to $974. For $191 more you can upgrade to the MSO2072A.
Because you were actually referring to the MSO2072A about which that comment was made (https://www.eevblog.com/forum/testgear/best-entry-level-oscilloscope-for-computer-engineering/msg753532/#msg753532 (https://www.eevblog.com/forum/testgear/best-entry-level-oscilloscope-for-computer-engineering/msg753532/#msg753532)):
When I woke up this morning I was heavy leaning towards an MSO2072A
Not sure what information you're referring to regarding the MSO on the DS1054Z: as far as I know, the DS1054Z doesn't have an MSO option. There was some talk recently that they might be introducing a version of the DS1000Z that might accept an after market MSO option, but I don't believe they're available as yet. At present, the only MSO option for the DS1000Z series on on the MSO1074Z and MSO1100Z.
The MSO on the MSO1074Z is OK in my experience.
What's not fantastic is the serial protocol decode (analogue or digital channels) because you can only decode and list what's on the screen, not what's in memory, and even then it undersamples the underlying display memory. In practice what this means is that although the scope might have an enormous buffer, you can't export a CSV of the decoded frames of the entire buffer, just the few bytes it can decode on the display. The protocol decode doesn't work on waveform recorded segments either (aka segmented memory). Although you can trigger on a given serial scenario (which does work with waveform record), you can't search on an already captured waveform. In I2C, it sometimes makes mistakes in decoding, although the I2C trigger works correctly. Having said that, it's without doubt better than no decode or trigger at all.
I've never used a DS/MSO2000A series so I'm afraid I can't comment on any limitations of protocol decoding on those.
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From what I hear the MSO option on the DS1054Z is worthless, so you would need to buy a DS1054Z plus a separate logic analyzer. The Saleae Logic Pro 16 costs $599. Now you're up to $974. For $191 more you can upgrade to the MSO2072A.
That would be true only if a MSO2072A is _an upgrade_ from a DS1054Z + Saleae Logic Pro 16. I don't think it is. I am not against a MSO, but my experience is that you can't accomplish the same work on a MSO that you can with a USB LA like the Saleae or Intronix LogicPort.
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I mean, what's the fastest 8bit ADC you can get on the component market these days, 4GSa/s or something like that? In scopes we're currently at 240GSa/s.
For general purpose chips the maximum sample rate of merchant parts is not that high. However, some specialist stuff is much faster. For example, you can find a presentation on the web about Fujitsu's 56Gsps and 80Gsps 8 bits ADCs for ethernet applications. Most of the chip is trying to deal with the never ending deluge of data flooding from the the converter. That's why it ends up as a specialist part, and not a pure ADC.
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From what I hear the MSO option on the DS1054Z is worthless, so you would need to buy a DS1054Z plus a separate logic analyzer. The Saleae Logic Pro 16 costs $599. Now you're up to $974. For $191 more you can upgrade to the MSO2072A.
That would be true only if a MSO2072A is _an upgrade_ from a DS1054Z + Saleae Logic Pro 16. I don't think it is. I am not against a MSO, but my experience is that you can't accomplish the same work on a MSO that you can with a USB LA like the Saleae or Intronix LogicPort.
Depends on the usage scenario but in general an MSO can do 95% of the logic analysis tasks. USB logic analysers are better at protocol decoding than low end MSOs like the ones from Rigol and Siglent. In case you need to do more complicated logic analysis tasks (complex triggers / higher speeds) getting a real logic analyser is a better choice because you'll have deeper memory, proper probes and better triggering capabilities. IMHO the Intronix Logicport is a bit of a toy due to the extremely short memory. You can make do ofcourse but I ran into it's limitations rather quickly.