Products > Test Equipment

Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)

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joeqsmith:

--- Quote from: SilverSolder on February 21, 2021, 04:42:11 pm ---Understanding vintage tech is always instructive.

One concrete goal might be to understand them better, so they can be kept in useful service for many years to come. There aren't many alternatives in this price range that have comparable specs, especially if you include AC in the comparison - so good examples are worth taking care of.

Another concrete goal might be finding a way to verify and perhaps even calibrate these meters (including aligning the A/D) assisted by a script running on the computer - so you could do it more often, with less calibration equipment (depending on how clever we can get), and thereby enjoy the benefits of having such a good specification meter in the first place - i.e. being able to use it for other electronics projects where measuring stuff very precisely / accurately is beneficial.

Everything depends on what we discover when we look under the hood.   If the code is a super complicated haystack, it won't be easy to do anything with it.  If there is some method to the madness in there, it may be possible to make changes - or it might be possible to leverage the fact that we know what it is doing, to "trick" it into something else.  Time will tell!  :D 

Going completely crazy, in theory, you could even make completely new modules to fit into the motherboard...    a truly crazy person could make a new controller board out of an Arduino, for example...   (I did say truly crazy!)   ;D

--- End quote ---

I was talking with a friend of mine about this old meter and I was suggesting making a new interface board for it that would act like the parallel interface but had Ethernet.   Basically just an FPGA, Phy, memory, clock and translators on the board.  Emulating the hardware would allow it to work without any firmware changes.   

There was a point when I had some sort of assembler/disassembler (for the 8080) that ran under CPM.   This was long after having to learn that part.  It may have ran on that old Televideo or the PC.   For the Televideo, I had a way to copy data to/from the old 5" floppy to DOS.  It seems like what ever I had would support the native mnemonics of the 8080 as well as the Z80.  Again,  this is going way way back.   When I had to learn the 8080, we were required to do everything by hand (paper and pencil).  You learned very quickly to sprinkle no-ops into your code.    :-DD   The programs were simple enough it wasn't too big of a deal.     

   

SilverSolder:

--- Quote from: joeqsmith on February 21, 2021, 05:56:44 pm ---
--- Quote from: SilverSolder on February 21, 2021, 04:42:11 pm ---Understanding vintage tech is always instructive.

One concrete goal might be to understand them better, so they can be kept in useful service for many years to come. There aren't many alternatives in this price range that have comparable specs, especially if you include AC in the comparison - so good examples are worth taking care of.

Another concrete goal might be finding a way to verify and perhaps even calibrate these meters (including aligning the A/D) assisted by a script running on the computer - so you could do it more often, with less calibration equipment (depending on how clever we can get), and thereby enjoy the benefits of having such a good specification meter in the first place - i.e. being able to use it for other electronics projects where measuring stuff very precisely / accurately is beneficial.

Everything depends on what we discover when we look under the hood.   If the code is a super complicated haystack, it won't be easy to do anything with it.  If there is some method to the madness in there, it may be possible to make changes - or it might be possible to leverage the fact that we know what it is doing, to "trick" it into something else.  Time will tell!  :D 

Going completely crazy, in theory, you could even make completely new modules to fit into the motherboard...    a truly crazy person could make a new controller board out of an Arduino, for example...   (I did say truly crazy!)   ;D

--- End quote ---

I was talking with a friend of mine about this old meter and I was suggesting making a new interface board for it that would act like the parallel interface but had Ethernet.   Basically just an FPGA, Phy, memory, clock and translators on the board.  Emulating the hardware would allow it to work without any firmware changes.   

There was a point when I had some sort of assembler/disassembler (for the 8080) that ran under CPM.   This was long after having to learn that part.  It may have ran on that old Televideo or the PC.   For the Televideo, I had a way to copy data to/from the old 5" floppy to DOS.  It seems like what ever I had would support the native mnemonics of the 8080 as well as the Z80.  Again,  this is going way way back.   When I had to learn the 8080, we were required to do everything by hand (paper and pencil).  You learned very quickly to sprinkle no-ops into your code.    :-DD   The programs were simple enough it wasn't too big of a deal.     

 

--- End quote ---

LOL!   :-DD

I never learned 8080, but I did once write a network driver in 8086 assembler in order to be able to "hit the metal" under DOS!  Those were the days...  today, you would be arrested by the IT department for trying anything like that!   :D


I guess the kind of code that is in this instrument is why all the modern software development methods were invented, as the haystack eventually becomes unmanageable!  :D

joeqsmith:
I wasn't able to locate my books on the 8080.   There was also a cheat sheet that was provided that had all of the instructions that I wasn't able to find.   Just artifacts from days gone by.

If you like old stuff though, here are two of the original Intel evaluation kits for the 8080.  Note the letter talking about the supplied PIOs.   Guessing these kits would be fairly rare.

****
https://en.wikipedia.org/wiki/Intel_System_Development_Kit

https://www.intel-vintage.info/inteldevelopmenttools.htm

SilverSolder:

--- Quote from: joeqsmith on February 21, 2021, 07:26:08 pm ---I wasn't able to locate my books on the 8080.   There was also a cheat sheet that was provided that had all of the instructions that I wasn't able to find.   Just artifacts from days gone by.

If you like old stuff though, here are two of the original Intel evaluation kits for the 8080.  Note the letter talking about the supplied PIOs.   Guessing these kits would be fairly rare.

****
https://en.wikipedia.org/wiki/Intel_System_Development_Kit

https://www.intel-vintage.info/inteldevelopmenttools.htm

--- End quote ---

Wow, nice bit of history!  Did you buy that originally?

The 8080 is the father of a pretty big wave of descendants...   including the one being used to type this comment, LOL...  has it reached self awareness?  :D

I love old tech.   How can you not fall for something like this:

Roman oh:

--- Quote from: m k on February 21, 2021, 11:30:33 am ---

I've recently wasted time with google.
Everyting seems to be plently first and then finally just junk.
I tried to find an i8080 emulator that would suite for hardware testing but found nothing.
Memory says that Altavista was better.

Obviously I had to start doing my own emulator, it's still just a shell but I'll upload it if it becomes usefull.
For a moment I thought maybe Ghidra addon can do it but then later there will be an avoidable obstacle anyway.

--- End quote ---

I couldn't find a useful 8080 emulator, but there seems to be a lot of 8085 stuff out there (100% code compatible with 8080, and just ignore the different external interrupt structure (RST 5.5, 6.5, 7.5); the 8080 interrupts RST0 - RST7 are treated as software interrupts in the 8085, but the code works fine).
I had some fun putting this code into an 8085 emulator that I downloaded from Oshon Software (no affiliation). The evaluation version is free, but closes after a one hour session, and you get 30 of those sessions for free. But the licence is only 25 euro. It allows breakpoints, single stepping, modify rom, ram and registers (very useful for shortening the start-up delay at 02E4H). I spent (won't say wasted - as SilverSolder says, it's all instructive) a couple of days trying to get my haed into the code, but it seems to the epitome of the reason why spaghetti code is frowned on. I suspect it may actually be the output of an early C compiler, or somesuch - I used one of those on my CPM system in the early 80s. The code flow threads around like <delete rude simile!>.
It transfers code into RAM, which you might do if, say you wanted to configure the code on the fly according to different models or somesuch, but the code it transfers to RAM looks like simple arithmetic operations, and they appear to be executed during start-up even before it does anything that looks like determining a model. (The Oshon simulator manages to execute these "RAM" instructions OK, but because they are not part of the loaded program (which, incidentally, it seems to disassemble OK) you can't "see" (ie trace and breakpoint) these steps. Would be simple enough to fudge, if one wanted to.
And it does other crazy things that a "human" assembly code programmer wouldn't do - eg, bunches of subroutines, 3 bytes long, clear the same memory locations twice in two different places, etc, etc, etc.
It was doing my head in... and I was only doing it "because I can".
So while I shall keenly track this thread, I don't think I'll be doing a lot more on this in the near term. But I got my 25Euro worth!

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