Author Topic: EEVblog #788 - Apple IIC Teardown  (Read 20553 times)

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Online EEVblog

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EEVblog #788 - Apple IIC Teardown
« on: August 27, 2015, 09:25:52 am »
Vintage retro teardown of an original Apple IIC

Schematics: http://www.applelogic.org/files/IICSCHEMATIC.pdf
Technical Reference Manual: https://archive.org/details/Apple_IIc_Technical_Reference_Manual
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Offline gemby

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #1 on: August 27, 2015, 10:24:00 am »
Huh, it was my dream machine back in the days, great teardown.
 

Offline rs20

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #2 on: August 27, 2015, 10:59:37 am »
Awesome  :-+

It seems anachronistic to me that such a compact computer has a big linear power supply... were switch mode AC/DC power supplies really not invented back then? Or was it cost saving to just use a big linear transformer running at mains frequency?
 

Offline Fungus

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #3 on: August 27, 2015, 12:16:13 pm »
Nice one...  :-+
 

Offline TheCynicalCris

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #4 on: August 27, 2015, 12:40:54 pm »
Damn, I love those vintage computer teardowns. Especially Apple machines, they aways put some extra effort into them =).
 

Offline Godzil

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #5 on: August 27, 2015, 01:32:28 pm »
Thanks dave for that teardown :)

Does the drive work better after the cleanup?
When you make hardware without taking into account the needs of the eventual software developers, you end up with bloated hardware full of pointless excess. From the outset one must consider design from both a hardware and software perspective.
-- Yokoi Gunpei
 

Offline VK3DRB

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #6 on: August 27, 2015, 01:42:49 pm »
Good tear down, which demonstrated good quality even though there were a few wire-adds. For its day, Apple did a pretty good job, but you paid for it.

In 1984 I bought a Rotten Apple from the notorious Golden Centre in the aptly named Sham Sui Po district in Hong Kong. The Golden Centre was the world's biggest software pirates den, often raided by Hong Kong police. The ground floor hosted around 200 or so tiny stores mostly selling pirated hardware and software by Triad foot soldiers. In the upper floors the criminal gangs were duplicating commercial software for minicomputers and PC's. I bought a pirated Apple II there for a fraction of the price of a genuine Apple. It was a piece of crap... full of hardware bugs and dodgy workmanship and design. But I was able to rebuild it to be reliable, like replacing every semiconductor and capacitor in the fake "Made in Japan" power supply. In the end, it served as a good machine.

In my opinion the best thing about Apples and Rotten Apples was an addictive strategy game called Conan  :-+. Not forgetting Sargon  :-+. And me old mate Print Shop  :'(. On that machine, I wrote software a Morse Code trainer in 6502 machine code (not Assembly Language, but actual machine code). I would never bother with machine code these days... no need. In fact, there is almost no need to bother with Assembly Language, as free C compliers are commonplace.

I sold the machine in 1986, upgrading to an IBM clone.
 

Online EEVblog

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #7 on: August 27, 2015, 01:50:06 pm »
Does the drive work better after the cleanup?

Seems to, yes. Some of the disks look physically damaged though.
 

Offline Godzil

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #8 on: August 27, 2015, 02:01:49 pm »
 :-+

I really like this machine, and try to get one for a normal price (I saw some people on ebay trying to sell them for more than 100€ untested, without the power brick etc.. :/) but without any luck right now.
This is a really neat version of the Apple ][.

By the way, the composite is capable of color in NTSC only if I remember correctly, and the RGB output may need an adaptor to works.
You are true that we can use the internal and external drive at the same time.

What impress me is that the main floppy motor belt is still good!
When you make hardware without taking into account the needs of the eventual software developers, you end up with bloated hardware full of pointless excess. From the outset one must consider design from both a hardware and software perspective.
-- Yokoi Gunpei
 

Offline Fungus

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #9 on: August 27, 2015, 03:04:31 pm »
In my opinion the best thing about Apples and Rotten Apples was an addictive strategy game called Conan  :-+.
http://www.virtualapple.org/conandisk.html
 

Offline Len

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #10 on: August 27, 2015, 04:19:28 pm »
It seems anachronistic to me that such a compact computer has a big linear power supply... were switch mode AC/DC power supplies really not invented back then? Or was it cost saving to just use a big linear transformer running at mains frequency?

The original Apple II had a switch-mode power supply (internal, not an external brick). I recall that switching supplies weren't the most common at the time, but certainly not unknown.
 

Online Dr. Frank

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #11 on: August 27, 2015, 06:22:27 pm »
Gorgeous Video, Dave!

Brought back many memories from my Apple ][e time (a clone, of course)

As far as I remember, back then, I also found that "jitter" on the CPU clock.
I think, it was sort of a bus / CPU hold state from the timing circuitry, either for the display (as it had no dedicated graphics chip), or for the DRAM refresh, (as it also had no dedicated memory management chip), or maybe both.
If I'm not mistaken, you should find about 1 extended clock phase on 100, so the effective clock rate was about 1% low.

The timing for all these periphery was the most trickiest part on these machines.

Great  :-+ :-+ :-+

Frank
« Last Edit: August 27, 2015, 06:37:51 pm by Dr. Frank »
 

Offline salfter

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #12 on: August 27, 2015, 07:17:15 pm »
As far as I remember, back then, I also found that "jitter" on the CPU clock.
I think, it was sort of a bus / CPU hold state from the timing circuitry, either for the display (as it had no dedicated graphics chip), or for the DRAM refresh, (as it also had no dedicated memory management chip), or maybe both.
If I'm not mistaken, you should find about 1 extended clock phase on 100, so the effective clock rate was about 1% low.

Every 65th CPU cycle is stretched by 2 cycles from the main 14-MHz (really 4x~3.58 MHz) clock:

http://mirrors.apple2.org.za/ground.icaen.uiowa.edu/MiscInfo/Empson/videocycles

This was done to get the numbers to work out correctly for NTSC video timing, as the core logic (implemented as a bunch of 74LSxxx chips in the II and II+, reduced to two chips in the IIe and IIc, and reduced further to one chip in the IIGS) interleaves memory access between the CPU and video generation. Memory is clocked at twice the CPU speed; on every other cycle, it's available to the CPU, while the video hardware gets it on the in-between cycles.  DRAM refresh is a side effect of video generation.  As a result, the CPU never has to wait for video generation or DRAM refresh.

Woz is an effin' genius.  :-+
 

Offline sunnyhighway

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #13 on: August 27, 2015, 07:24:36 pm »
Seems to me this video was originally planned to be published in the year 2025

 

Offline Fungus

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #14 on: August 27, 2015, 07:35:22 pm »
the core logic (implemented as a bunch of 74LSxxx chips in the II and II+, reduced to two chips in the IIe and IIc, and reduced further to one chip in the IIGS) interleaves memory access between the CPU and video generation. Memory is clocked at twice the CPU speed; on every other cycle, it's available to the CPU, while the video hardware gets it on the in-between cycles.  DRAM refresh is a side effect of video generation.  As a result, the CPU never has to wait for video generation or DRAM refresh.

Woz is an effin' genius.  :-+
Interleaved CPU/video was fairly standard practice at the time (it avoids display glitches and got you DRAM refresh for free).

I want to know what the 555 timers are for...
 

Offline German_EE

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #15 on: August 27, 2015, 09:14:43 pm »
One of the peripherals you could get for the Apple // series were a pair of Game Paddles, just a variable resistor inside but they were still expensive. Each half of the 556 timer chip had its frequency (and therefore its position) set by a paddle.

Hi to all the ex members of Manchester Apple Users Group who used to meet in the Staff House at UMIST.
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Offline richfiles

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #16 on: August 27, 2015, 09:24:33 pm »
The third (hardware) revision of the //c updated the keyboard to use Alps Amber mechanical keyswitches. They seem similar to Cherry Blue, but with a little more force required to press. These were used int he latter half of the first version (rev 3 was the memory expansion version). The keyboard has an aluminum key plate to give it it's rigidity, and ditched the plastic brace of the Rev 1 and 2 variants. The //c Plus is the one with the 3.5 inch floppy, and the slider volume. I believe it used Alps Orange keyswitches, which are what the IIgs keyboard used. I think those were a linear switch... The Ambers were tactile... clicky-clicky!  :-+

There actually were a couple keyboard layouts. Some European layouts used the keyboard switches, not for a Dvorak layout, but for additional international character layouts. It ended up being used for Dvorak simply because the switch was already there.

I'm installing this keyboard in a Kerbal Space Program "Command Module" themed controller, similar to the one Dave played at the Sydney Maker Faire!

« Last Edit: August 27, 2015, 09:34:28 pm by richfiles »
 

Offline Towger

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #17 on: August 27, 2015, 09:52:51 pm »
Brings back memories, cutting the notch out of the other side of the floppy disk, so you could turn it over and use it on the single sided drive.
 

Offline dentaku

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #18 on: August 27, 2015, 10:01:15 pm »
I like that you did some research before recording this teardown and stopped to research more stuff while doing it too. It just make for a more enjoyable and less waffle-filled video :)

I hope someone sends you some old marine electronics sometime (Furuno stuff with all through hole parts) but more importantly old Roland, Korg, Sequential Circuits or Moog stuff.
I hope you get time to do the giant mixing board video soon but I assume that you probably need to be single like Mike Harrison to find the time to tackle the ultrasound machine.
 

Offline Godzil

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #19 on: August 28, 2015, 12:13:20 am »
the core logic (implemented as a bunch of 74LSxxx chips in the II and II+, reduced to two chips in the IIe and IIc, and reduced further to one chip in the IIGS) interleaves memory access between the CPU and video generation. Memory is clocked at twice the CPU speed; on every other cycle, it's available to the CPU, while the video hardware gets it on the in-between cycles.  DRAM refresh is a side effect of video generation.  As a result, the CPU never has to wait for video generation or DRAM refresh.

Woz is an effin' genius.  :-+
Interleaved CPU/video was fairly standard practice at the time (it avoids display glitches and got you DRAM refresh for free).

In fact, as Dave quoted during the video, the 6502 have 3 phases clocks, Phi0, Ph1 and Phi2. Phi0 is the main clock, and is an input on the 6502, Phi2 is the "external device" clock or I you say, the clock is used to know when the 6502 is not using the Address and Data bus. Phi1 on the contrary is the reverse.

The 6502, divide the main clock in 3 parts, 1 for A/D bus access and 2 for internal work, so clever device like the Apple 2 use Phi2 to know when the 6502 is doing it's internal work, and the external hardware (the video generator in this case) steal the bus for the 2 period where the 6502 doesn't use the bus.

Some other 6502 base computer also used the same trick (like the Oric 1/Atmos) where the video chip use the same steal method as the Apple ][. The problem on this specific computer (and some other I presume) is that the Phi2 output of the 6502 is not made to be directly used, and should be buffered before anything. And when you look at the shape of the Phi2 output you'll understand why.. It's just awful and nearly does not looks like a clock.. :D This is because this output is not buffered inside the 6502.
When you make hardware without taking into account the needs of the eventual software developers, you end up with bloated hardware full of pointless excess. From the outset one must consider design from both a hardware and software perspective.
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Online EEVblog

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #20 on: August 28, 2015, 12:32:25 am »
What impress me is that the main floppy motor belt is still good!

Yes, quite surprising.
 

Offline Godzil

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #21 on: August 28, 2015, 12:36:12 am »
What impress me is that the main floppy motor belt is still good!

Yes, quite surprising.

The number of 198x floppy drive that use a belt for the main motor, where the belt is completely dead (how do you say that dave ? Goneski?
Most of the 3" drive of the CPC6128 no longer work because of that, most of the Nintendo Famicom Disc System are not working because of that, and all of them are about 1985/1986 vintage
When you make hardware without taking into account the needs of the eventual software developers, you end up with bloated hardware full of pointless excess. From the outset one must consider design from both a hardware and software perspective.
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Offline salfter

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #22 on: August 28, 2015, 02:31:25 am »
I want to know what the 555 timers are for...

Joystick port. One 555 for each axis. Charge up a capacitor, discharge it through the potentiometer in the joystick, and use the CPU to count how long it takes to discharge. There was a ROM routine (and a BASIC command) that did all of that for you, but you could write your own code if you wanted to measure resistance values beyond what would've been used in joysticks.

Other Apple IIs used a 558 to support two joysticks. I started with a IIe in 1985, which I upgraded to a IIGS (by way of a motherboard swap) around 1992 or '93. Still have it, as well as some more Apple IIs I've picked up cheap through the years. Never had a IIc, though.
 

Offline Fungus

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #23 on: August 28, 2015, 03:09:56 am »
I want to know what the 555 timers are for...

Joystick port. One 555 for each axis. Charge up a capacitor, discharge it through the potentiometer in the joystick, and use the CPU to count how long it takes to discharge.
Oh, of course. I forgot that's how they used to read joysticks.
 

Offline Rasz

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #24 on: August 28, 2015, 05:47:50 am »
What a terrible computer :(

All the clever Wozniak hacks are only neat from the hardware startup perspective. They were useful when Apple was launching, but made this computer pretty archaic and bad in 1984. Saving few cents for the price of no real floppy error correction (sum of all bytes instead of industry standard crc, trivial to miss errors) and cpu hogging (all the floppy decoding in software). Same for graphics, no sprites no scrolling, all the color modes with idiotic bit patterns/interleave and limitations (140x192 of real usable resolution and so on).

Its not like Apple was struggling, they were selling this pos  at >$2000, they had HUGE profit margins. Whole Apple 2 line was what kept Apple alive for a long time (deep into Mac era). $50 million blown on failed Lisa alone is a testament of fat profits on Apple 2.

c64/Atari 800xl creamed it when it comes to graphics, sound and price. I wonder what could of been if Visicalc didnt start on Apple2.
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Online BradC

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #25 on: August 28, 2015, 05:59:28 am »
c64/Atari 800xl creamed it when it comes to graphics, sound and price.

They probably did, but without the benefit of an established user base and backward compatibility they remained toys with niche markets. Apple had a niche too, it was just a lot bigger. The Commodore saw a lot of use as a home games machine, but with it's crap keyboard it never went anywhere in the business world, and the Atari remains an (albeit clever) also-ran.

You may look at the old Apple stuff as archaic with the benefit of your years of expert experience and those 30 years of hindsight, but for those that used them on a day to day basis they offered a utility that was hard to match, and their sales proved it.

The //c was a bit of an anomaly that never really worked. It was clever though.
 

Online coppice

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #26 on: August 28, 2015, 06:23:15 am »
What a terrible computer :(

All the clever Wozniak hacks are only neat from the hardware startup perspective. They were useful when Apple was launching, but made this computer pretty archaic and bad in 1984. Saving few cents for the price of no real floppy error correction (sum of all bytes instead of industry standard crc, trivial to miss errors) and cpu hogging (all the floppy decoding in software). Same for graphics, no sprites no scrolling, all the color modes with idiotic bit patterns/interleave and limitations (140x192 of real usable resolution and so on).

Its not like Apple was struggling, they were selling this pos  at >$2000, they had HUGE profit margins. Whole Apple 2 line was what kept Apple alive for a long time (deep into Mac era). $50 million blown on failed Lisa alone is a testament of fat profits on Apple 2.

c64/Atari 800xl creamed it when it comes to graphics, sound and price. I wonder what could of been if Visicalc didnt start on Apple2.
This thing was introduced to be compatible with older machines. Sure, its floppy scheme was crude, but anything else would not read and write disks compatible with an Apple ][. Sure its graphics were crude, but that was kind of imposed by the need to run Apple ][ code. There must have been a market for people wanting this, although most of us scratched our heads and couldn't figure out why anyone would pay so much for such a machine.

The really strange machine was the update with a 3.5" floppy drive. Without backwards compatibility, it seemed to have no purpose at all.
 

Offline Fungus

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #27 on: August 28, 2015, 09:42:25 am »
c64/Atari 800xl creamed it when it comes to graphics, sound and price. I wonder what could of been if Visicalc didnt start on Apple2.
So?

Not everybody wanted a computer to play games. Some people just wanted a compact machine with business-like software.

A C64/Atari kitted out with floppy disks, printer interface, etc, would have cost about the same as the Apple but  have a lot more wires and take up a lot more desk space. And it wouldn't have the software.

all the floppy decoding in software
Unlike the C64...



(I don't know anything about the Atari floppies)
 

Offline Delta

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #28 on: August 28, 2015, 09:47:59 am »
The c64 disk drives had their own 6502 processor!

The fastloader were to overcome the fact that Commodore used a shitty software based serial bus implementation, due to a bug with the shift register on a CIA chip that was planned to run the bus...
 

Offline Fungus

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #29 on: August 28, 2015, 09:59:03 am »
The c64 disk drives had their own 6502 processor!
I know!

The fastloader were to overcome the fact that Commodore used a shitty software based serial bus implementation, due to a bug with the shift register on a CIA chip that was planned to run the bus...
Did fastloader reduce CPU overhead? Did it transfer the data at full hardware speed using DMA?

That's what floppy disk controller chips are for.

The Apple didn't have one, the C64 didn't have one and I'm fairly sure the Atari didn't one either (Atari floppy drives were on a proprietary serial bus just like the C64).

 

Offline Godzil

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #30 on: August 28, 2015, 10:04:49 am »
The really strange machine was the update with a 3.5" floppy drive. Without backwards compatibility, it seemed to have no purpose at all.

I don't agree, the IIgs came with a 3.5" drive at that time the industry was moving our of the 5.25" driver and floppy, making a computer that still used per default them would have been silly. And it's not like you wouldn't been able to plug a real 5.25" drive with the back connector.

BTW, Dave, I'm sure you really want to play that Zork II game on you nice //c, my recommandation is to go to the Apple ][ Asimov ftp (google will help) they store virtually everything about the Apple ][, and use the ADTpro tool ( http://adtpro.sourceforge.net/ ) to rebuild a floppy from the image.

ADTpro is a really good tool and helped me numerous times to rebuild dead Apple ][ floppy and allow to bootstrap an Apple ][ DOS3.3 / ProDOS when you don't the floppy to boot them. Really handy, a must have tool for every Apple ][ users..
When you make hardware without taking into account the needs of the eventual software developers, you end up with bloated hardware full of pointless excess. From the outset one must consider design from both a hardware and software perspective.
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Offline Ketturi

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #31 on: August 28, 2015, 11:26:43 am »
Very nice retro teardown.
Are those red nippon chemi-con caps someway special? I have seen them on some "mission critical" equipment like in solid state electricity meters.
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Offline Delta

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #32 on: August 28, 2015, 11:29:48 am »
The c64 disk drives had their own 6502 processor!
I know!

The fastloader were to overcome the fact that Commodore used a shitty software based serial bus implementation, due to a bug with the shift register on a CIA chip that was planned to run the bus...
Did fastloader reduce CPU overhead? Did it transfer the data at full hardware speed using DMA?



Heh, no way!  The best fastloaders used 100% CPU time (and blanked the display to prevent the video chip stealing extra cycles for additional DMA fetches every 8 raster lines) in order get get extremely tight timing to be able to send data asynchronously using the data AND clock lines on the bus.

Very clever stuff 😀
 

Offline Godzil

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #33 on: August 28, 2015, 01:25:20 pm »
On the Apple ][ Disabling the display (and on every well made 6502 computer that use the "dead time cycle" time to read memory for display) it does not give any boost

That would mean that the C64 is not a well made computer :p
When you make hardware without taking into account the needs of the eventual software developers, you end up with bloated hardware full of pointless excess. From the outset one must consider design from both a hardware and software perspective.
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Offline Delta

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #34 on: August 28, 2015, 02:15:40 pm »

That would mean that the C64 is not a well made computer :p

HOW VERY DARE YOU!!!! 😡😡😡

/capslock
/c64fanboy
😉
 

Offline German_EE

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #35 on: August 28, 2015, 03:30:24 pm »
One thing I could never figure out on the //c was the way they placed the RAM on the board. In theory a line of sixteen chips like that should give horrible timing problems but, somehow, they managed it. More magic sauce from Woz perhaps.
Should you find yourself in a chronically leaking boat, energy devoted to changing vessels is likely to be more productive than energy devoted to patching leaks.

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Offline Godzil

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #36 on: August 28, 2015, 05:07:38 pm »
All chip is a 1bit dram memory, and we are speaking about a 2 or 3Mhz memory access! So the timing difference between each chip is nearly irrelevant
When you make hardware without taking into account the needs of the eventual software developers, you end up with bloated hardware full of pointless excess. From the outset one must consider design from both a hardware and software perspective.
-- Yokoi Gunpei
 

Offline SeanB

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #37 on: August 28, 2015, 06:10:18 pm »
They also used the fastest chips. IIRC they would buy up entire untested batches of chips, and screen them for the fastest chips for use on the boards, then simply sell the ones that were still fully functional but too slow onto the open market again, recouping a lot of the test cost. If you only need a part to be faster than 120ns, and need to buy them in ton lots, doing your own sort was worth it to get the best chips out, then simply batch the rest into a speed group and sell them as tested chips to others. The markup probably covered the test cost, and this was at a time when DRAM was expensive and in short supply driving up prices. Only a few years later did an oversupply cause a price crash, as the foundries all were trying to cash in on the high prices and Moore's law meant they all were eventually losing money on them.
 

Offline Godzil

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #38 on: August 28, 2015, 06:19:02 pm »
DRAM was expensive but much less than SRAM or this would be meaningless to use DRAM
When you make hardware without taking into account the needs of the eventual software developers, you end up with bloated hardware full of pointless excess. From the outset one must consider design from both a hardware and software perspective.
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Offline Rasz

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #39 on: August 29, 2015, 12:09:22 am »
Not everybody wanted a computer to play games. Some people just wanted a compact machine with business-like software.

commodore/atari were popular as business machines in Europe, up until IBM clones took over in late eighties

A C64/Atari kitted out with floppy disks, printer interface, etc, would have cost about the same as the Apple

not even close, try half the price of naked Apple 2, quarter if you compare first Macs to Atari ST.

all the floppy decoding in software
Unlike the C64...

Yes, unlike c64/atari. C/Atari did all of the decoding on the floppy, and transferred sector data instead of raw bitstream. That means less main CPU spend while loading. Of course they had their own problems insisting on serial communication, Commodore shipped broken silicon, Atari shipped working, but hilariously slow SIO (128kbit).


That's what floppy disk controller chips are for.

The Apple didn't have one, the C64 didn't have one and I'm fairly sure the Atari didn't one either (Atari floppy drives were on a proprietary serial bus just like the C64).

Apple didnt have one. c64 got one after 1541, Atari also used proper Western Digital controller chips, of course both companies decided to build additional separate 6502 computer inside floppy drive and link them over super slow serial link with main machines (W T F) instead of utilizing cartridge slot(why?).

Commodore, being Commodore with head in the ass, moved backward with Amiga and copied Apple. Again cpu had to do all the work resulting in subpar error correction (XOR instead industry standard crc16), not to mention custom silicon was speed limited forcing later models to use another 'clever' (read stupid) hack in form of spinning HD disks at half the speed (half read speed as a bonus!).
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Offline Godzil

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #40 on: August 29, 2015, 11:02:09 am »
And 30 years after the Apple II disk and drive still work.

How many C64 drive/floppy still work?
When you make hardware without taking into account the needs of the eventual software developers, you end up with bloated hardware full of pointless excess. From the outset one must consider design from both a hardware and software perspective.
-- Yokoi Gunpei
 

Offline timofonic

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #41 on: September 01, 2015, 01:33:51 am »
I want to know what the 555 timers are for...

Joystick port. One 555 for each axis. Charge up a capacitor, discharge it through the potentiometer in the joystick, and use the CPU to count how long it takes to discharge. There was a ROM routine (and a BASIC command) that did all of that for you, but you could write your own code if you wanted to measure resistance values beyond what would've been used in joysticks.

Other Apple IIs used a 558 to support two joysticks. I started with a IIe in 1985, which I upgraded to a IIGS (by way of a motherboard swap) around 1992 or '93. Still have it, as well as some more Apple IIs I've picked up cheap through the years. Never had a IIc, though.

Those old tricks seem interesting. I wonder if they provide a DAC able to put analog inputs on them.

I never had a pre PC Compatible computer. My first computer was a Pentium 100MHz. But I love retrocomputing and retrogaming in an obsessive way, it's part of my personal madness to 80s and early 90s stuff, but I like these classic chips too.

My personal dream is design highly functional, robust, innovative and cheap OSHW for vintage systems. 99% designs are  propietary, some of the most interesting ones use somewhat complex chips (SRAM, FLASH, FPGA, CPLD) and the most complex ones are those that reimplement original Hardware as replacement chips  improvements (this happens specially in video chips, see, VBXE2 for Atari XL/XR and for Amiga OCS/ECS/AGA) to most of the time they also add  features and provide more modern video photos proud outputs such VGA/DVI/HDMI with different scaling modes)

Apple IIGS! The inspiration of Super Nintendo/Famicom! It has a very good audio chip!

http://www.callapple.org/software/announcing-apple-iigs-system-6-0-2/

https://youtu.be/Wu9a724Az3E

Naughty Dog started developing on it.

Dave, please make a good teardown of it if you can! It's an American machine and not so easy to get, but maybe you're lucky!

I only found the following, not do good teardowns like yours :(











Like in other systems, there are expanding. Both old and new:







Some games:











https://youtu.be/IsXPn6OCMF8









There's some demoscene:











And nice music:











Some videos and ads:













I liked your X68000 teardown a lot. It's an amazing machine with tons of excellent arcade ports, some exclusive games and lots of those horny cartoon games (hentai, eroge). It has a bunch

Here we have the modest Sinclair ZX Spectrum 128K, maybe I'll send one if get money next year plus some (hopefully) own Hardware design.
« Last Edit: September 01, 2015, 02:02:00 am by Circuiteromalaguito »
 

Offline Godzil

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #42 on: September 01, 2015, 01:00:37 pm »
Unfortunately, unlike the X68000 which have a lots of electronics inside, and is hard to teardown, the IIgs will show even less than the IIc.

Computers that could be nice to teardown are the SGI O2 and the Octane, they are quite complexe computer, but not cheap and especially heavy computer :D
When you make hardware without taking into account the needs of the eventual software developers, you end up with bloated hardware full of pointless excess. From the outset one must consider design from both a hardware and software perspective.
-- Yokoi Gunpei
 

Offline timofonic

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #43 on: September 02, 2015, 12:35:44 am »
Unfortunately, unlike the X68000 which have a lots of electronics inside, and is hard to teardown, the IIgs will show even less than the IIc.

Computers that could be nice to teardown are the SGI O2 and the Octane, they are quite complexe computer, but not cheap and especially heavy computer :D

I don't care just about the complexity of the design, but a proper explanation with proper details from a good EE.

Simple stuff could be beautiful because of it's simplify

There's also arcade boards in the 16/32 range with complex breadboards too.

I'll propose Dave or futon moderators a retrocomputing/retroconsoles section when having time. The rest of forums have retro users that most are even more electronics illiterate than me.
 

Offline tpw_rules

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #44 on: September 02, 2015, 12:49:11 am »
In case anybody cares, I know too much about the internals of Zork and its brethren.

It's actually a pretty advanced system. The games are all in an interpreted language which means that once the base interpreter (the Z-machine) is ported to a given computer, all the games automatically become available for that computer (of course there are different versions of this language but you get the idea). The games are divided into a resident and disk portion. Zork 1's resident is 9K and the disk is 83K. Only the resident portion can be written by the interpreter, and it is loaded into memory at the start of the game. The disk portion contains code, data, and text, and is paged in and out when needed. The first command would page in a lot of text analysis and parsing routines but since you have 128K it would never get paged out. This system has the advantage of course that any computer with 9K of ram + whatever the interpreter (if available) uses can play Zork without modification to Zork's binary at all. Automatically loading in more would require the interpreter know what parts of the game do what and would increase time from boot to prompt.
 

Offline Godzil

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #45 on: September 02, 2015, 01:31:43 am »
Unfortunately, unlike the X68000 which have a lots of electronics inside, and is hard to teardown, the IIgs will show even less than the IIc.

Computers that could be nice to teardown are the SGI O2 and the Octane, they are quite complexe computer, but not cheap and especially heavy computer :D

I don't care just about the complexity of the design, but a proper explanation with proper details from a good EE.

Simple stuff could be beautiful because of it's simplify

There's also arcade boards in the 16/32 range with complex breadboards too.

I'll propose Dave or futon moderators a retrocomputing/retroconsoles section when having time. The rest of forums have retro users that most are even more electronics illiterate than me.

I doubt there is really a lot of thing to explain, th IIgs is a really simple design if you compare it to the ][(e) or the //c

A "nude" IIgs contain only the power supply and the mainboard nothing more, and the mainboard is nearly empty, you will find the ROM, the VGC (Video Graphic Controller) the MegaII and that nearly all you can find.

I have some photo of the internal of my own IIgs I could put them here if you want
When you make hardware without taking into account the needs of the eventual software developers, you end up with bloated hardware full of pointless excess. From the outset one must consider design from both a hardware and software perspective.
-- Yokoi Gunpei
 

Offline timofonic

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #46 on: September 02, 2015, 03:00:31 pm »
Unfortunately, unlike the X68000 which have a lots of electronics inside, and is hard to teardown, the IIgs will show even less than the IIc.

Computers that could be nice to teardown are the SGI O2 and the Octane, they are quite complexe computer, but not cheap and especially heavy computer :D

I don't care just about the complexity of the design, but a proper explanation with proper details from a good EE.

Simple stuff could be beautiful because of it's simplify

There's also arcade boards in the 16/32 range with complex breadboards too.

I'll propose Dave or futon moderators a retrocomputing/retroconsoles section when having time. The rest of forums have retro users that most are even more electronics illiterate than me.

I doubt there is really a lot of thing to explain, th IIgs is a really simple design if you compare it to the ][(e) or the //c

A "nude" IIgs contain only the power supply and the mainboard nothing more, and the mainboard is nearly empty, you will find the ROM, the VGC (Video Graphic Controller) the MegaII and that nearly all you can find.

I have some photo of the internal of my own IIgs I could put them here if you want


I understand the PCB might be simpler, but the ICs can be a lot more complex.

That's what I like to know too. The PCB design might look damn simpler because better Integration into ICs, but the whole thing is a lot more complex once you look at the inside those tiny black bricks :D

Apple IIGS has a very nice audio system too and the first Apple system to feature ADC.
 

Offline Godzil

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #47 on: September 02, 2015, 03:49:41 pm »
Ok ok, as soon as I have my IIgs with me, I will make a thread with some specific photos and comments about it
When you make hardware without taking into account the needs of the eventual software developers, you end up with bloated hardware full of pointless excess. From the outset one must consider design from both a hardware and software perspective.
-- Yokoi Gunpei
 

Offline RupertGo

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #48 on: September 02, 2015, 04:04:46 pm »
I'd love to see an Amstrad PCW8256 teardown. That was an astonishing piece of consumer design - extremely low chip count, but managed to be a fully integrated computer/monitor/printer device that cost much less than anything remotely comparable.

It even managed to do without a boot ROM.



 

Offline TheNewLab

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #49 on: September 03, 2015, 10:24:43 pm »
Hey!
I still have an Applce IIc. I used it for a small business from 1984 through 1995. version 1.01 Appleworks and Dollars and $ense. I even got a Micro Orange adapter to connect the system to a HP portable DeskJet.

In fact, I still use  MacOS 9.1 on one computer to run MYOB an accounting application.  Handles payroll and large inventories. Prints out all the forms and financial analysis reports I can dream of.  Besides MYOB changed their name and only offers a "Cloud" application and storage. Weren't personal computers all about getting control of our own data?

Regarding the Apple IIG, a film processing lab by the same name above. used one from 1990 until they closed in 2007. In fact, as Apple got to MacOS 7.0 they began buying up all they could. They had an entire shelf of IIG's just in case the original machine went down. the it was the only program that could print four lines of the Paco plastic slides mounts.
 

Offline TheNewLab

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Re: EEVblog #788 - Apple IIC Teardown
« Reply #50 on: September 03, 2015, 10:28:40 pm »
and 128K was a lot of memory back then...In fact. just to get 20Mb it required a machine about the size of 3 brief cases. 120v AC and a fan the size of an auto radiator fan running constantly.
 

Offline Godzil

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A
« Reply #51 on: September 03, 2015, 10:37:34 pm »
The earliest macintosh I still have, which is a Macintosh SE, still have it's 20MB hard drive, and it still work ! (nearly the same as dave did a teardown, mine have a 1.4MB capable floppy drive, it's one of the latests version of the SE)

And I still have a backup of that drive in 9 floppy if I remember correctly... :D
When you make hardware without taking into account the needs of the eventual software developers, you end up with bloated hardware full of pointless excess. From the outset one must consider design from both a hardware and software perspective.
-- Yokoi Gunpei
 

Offline Godzil

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EEVblog #788 - Apple IIC Teardown
« Reply #52 on: October 16, 2015, 10:48:57 am »
Hi Dave, I would like to request your help with your own Apple IIc.

I've got one last weekend, but the video output is not working, or should I say, the video signal is not what a composite screen would expect. There is an existing cable from the video, called Chat Mauve that transform the non standard "video out" signals to scart RGB, I didn't tested mine, but it seems that it also does not work.

Apart from the missing video, the IIc seems to work as it try to read a floppy, react to Ctrl+Reset, and basic seems to works as I manage to make it doing funny beeps.

What I've already done is to check the +5V rail, it's wobling a bit between 4.8 and 5.2V (it seems to be a 50Hz wobble, need to check that) it's far from perfect, but as the rest of the device work I would says that it's OK, but still need to check the caps in the DC2DC converter.

The other things I've checked are the signal comming to and from the SIL chip dubbed "VID" referenced as UE1 and was going to check the signals that goes out of the "digital" video output connector:



I will attach, or put in another post the screen captures from my scope of all of this signals

I would like to know Dave if you could do a capture of all of this signal from you own IIc as I don't have any reference here for these signals
And if anyone on this forum that knows how the video generation works in a IIc could help me to check what is wrong, I would be really grateful.

I'm absolutely not an expert in video signals and don't really understand what the UE1 thing is there for.
I suspect it's something about mixing the SEROUT signal (comming from the CHAR GEN) to pin 1, the SYNC signal (pin 2), CREF (color Ref, pin3) and CLRGAT, but how? I have no ideas.


Edit: interesting, SEROUT is now completely flat, I'm sure it wasn't yesterday, and CHARGEN is clearly outputting something, so the culprit could be the 74166 (marked as a LS on the schematic, but is really a HCT, go figure)
« Last Edit: October 16, 2015, 12:35:54 pm by Godzil »
When you make hardware without taking into account the needs of the eventual software developers, you end up with bloated hardware full of pointless excess. From the outset one must consider design from both a hardware and software perspective.
-- Yokoi Gunpei
 


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