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Vintage computer fun

Ok, so this happened:

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It’s a not entirely sane Apple II Europlus. As can be seen from the screen it boots to the ‘Apple ][‘ prompt, beeps, and has a flashing cursor, which is all good. The issue is at present it will only respond to ‘ctrl-reset’, no other keys work. It is also only loaded with one RAM bank at present, so 16KB. With the disc board and drive connected it does seek, so there is clearly a lot right about the mainboard. I have a feeling that is all fine and the problem lies in the keyboard controller board. The fact ctrl-break works gives me some faith that the physical keyboard mechanism is ok. I stripped and cleaned it and can see no obvious faults here.

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I’m posting at this point as I’m blown away by just how good a picture of the mainboard I could get with an iPhone 13 and a bit of cropping and perspective correction on my iPad! Full resolution here on Flickr. It is more than good enough to do some cross-checking, reading chip codes etc. It makes it so easy to have a record of exactly what is where on this specific example.

I checked the PSU, blown Rifa cap, obviously, but no leaks or bulges beyond that and all voltages are correct. I will obviously fully recap it in time, but not my main priority. I want to get it working first. Fix, then restore!

PS Depending how far in I get I may well end up respraying the case as it is has obviously worn through the paint around the front edge. I’m undecided here, but certainly not a priority.
 
Did you build it yourself?

Our Atom was factory built, I didn't have the courage to build one.

Just looking at Tony L's Apple II, really nice machine and at the time wowed with its 'color graphics' capability.

I was working in R&D at the time this was a thing and we had a mix of PDP 11's, Commodore PETs and other Intel and Ti based prototype board computers. I remember trying to convince them to buy a couple of Apple II's for our next project, but they (understandably) were having none of this, a). because I was a graduate angling for a fun toy to play with and b). because from a computational point of view it didn't really offer our tasks any thing over and above the PETs except for looks and "frivolous color graphics", their words not mine.

Yes of course we should have bought a couple !
 
The Apple II’s colour capability was a very clever hack, but it was still a hack. Describing how it works would probably need a description of how analogue composite video works, which would need a description of what phase-modulation is, but Woz didn’t bother with that theory stuff, so I won’t: he just realised that if you sent a very fast-cycling bit pattern out of a composite video output, a colour monitor would interpret it as a solid colour. So, he played with the timing to get stable colours, and the result was Lo-res graphics. The reason the 16 colours are so oddly chosen is because that’s just what you get from the possible 4-bit patterns (actually, there are only 15 colours, as the grey#1 0101 and grey#2 1010 are identical). Doing it this way meant that the video output circuitry could be implemented entirely with digital logic, with no need for any additional chips. That’s another thing Woz was good at: super-minimal chip-count designs: he also did some crazy things with the display memory layout on the Apple II simply so that he could avoid a needing to include a DRAM refresh circuit - the layout of the screen is odd, but it ensured that every row of the RAM chips was accessed continuously simply because the display is constantly being generated...

It’s so skanky it’s beautiful.
 
... That’s another thing Woz was good at: super-minimal chip-count designs: he also did some crazy things with the display memory layout on the Apple II simply so that he could avoid a needing to include a DRAM refresh circuit - the layout of the screen is odd, but it ensured that every row of the RAM chips was accessed continuously simply because the display is constantly being generated...
"An engineer can do for a dollar what any fool can do for two."
 
Woz was remarkably clever and radical, many really cool things like that, e.g. the way the disk drive logic works, the whole mainboard architecture, card slot architecture etc. Sadly the colour thing is only NTSC, it doesn’t translate to Pal or composite so this Europlus will be very much monochrome!
 
My Apple ][ is painted grey, with a fiber charged plastic. I had a later example that had a plastic case.
I have a colour card called Le Chat Mauve, which is RGB. But there is also a Z80 (Microsoft) card, a mouse card, a printer card, a series MoDem card. It uses a Duo Disk. I’ll take a photo of that.
 
Yes, that was the problem with some of Woz’s designs, they were super-specific to the problem at hand, and they needed complete replacement if any small thing changed. PAL would have needed different timing, and additional logic to deal with even and odd scanlines (the colour signals change to opposite phase on every scanline, hence the name), but the colours would have been different (the Atari 2600 had far more sophisticated video output hardware than the Apple II, but it still had the problem of different colours on PAL vs NTSC vs SECAM); SECAM just couldn’t have been done at all that way (SECAM used an FM sub-carrier for colour).

Apple did make an add-on card that re-enabled colour for PAL displays, but they are super-rare - you’ll probably have to pay as much for an Apple one as you did for the computer.
 
My Apple ][ is painted grey, with a fiber charged plastic. I had a later example that had a plastic case.

Mine is certainly painted and with a slightly textured structure-coat. You can see how it has worn off on the front edge exposing the yellowed plastic underneath. That aside I’m really impressed with the build quality of this thing. The case is remarkably solid, brass inserts for the case screws etc. It is a very strong construction. Assuming I can get it working properly I’ll almost certainly repaint it assuming I can find a good colour match in a suitable rattle-can plus primer. Being matt and textured it should be within my capabilities, e.g. I’d not try and strip it, just give it an even better clean that it’s already had (the case was in the bath for about two hours yesterday!), prime it and spray it some appropriate beige/almond. I’ll try to match the drive as that is painted metal and I think a more accurate shade. The Apple II case and its top are actually different shades! I got the logo off as part of the cleaning process, that is just resting in there at present. I do also have a much tattier second drive, but I suspect it is only valid as spares, the head mech seems very stiff. The good one in the picture gives the impression of at least trying to work. It spins, seeks etc. I’ve already cleaned it thoroughly.
 
Yes, textured paint, exactly. The graphic card is the one with the RGB adjustment Pihers.

1UUjeL1pNsJnvNOMpOpPXSNkDoqfyg6fSvv0YkU6lNfpBMG76QNMB0dVNolquzjQk3zIO_2XJ38wV97lPwl5CmZ10MiS30yhBjfZSDCvJlo-HujPZmRIh2t1Vk8CgrEZrHNA01rhq1qbZlEAvbOHF-bAd-i0UqOsu8DWagfQ_jZDZ6NqJBbNJA5iStOv9aVGTFPXPCvU4j5t2V8HYtAzaTh0-FmVO3y2Fhs3NU55vi24Q6OztYOuP9Dvh5sOP0udpaIxqYhBxsVQF4LSBWRMklCYfctJ_Chz03YYUsh-vZPZhuCW2KT03tWYh6nsHHTstcPVvKwbBJz7fGP3S3-1Vv01ucnggDRyiTHFI9LjXcl0n_r4cQShQfeqS85Fep5tf-Mpz1YbAKVZvv4DkllLGnWAUKMiViTE-W0uFDmIvIyy7Qx5Ys5PLci3HgC34Jp_PQCRHAdAbgL08kv53UzM5ZuccSIwtkEoIsNQodiDP0-USmb5x4s3xVYFXEDE6OHwgOT7O-ZQlWTzUORbvqfaqYk6X64z1WaXR6bih5QNxAf38jfGKcNDRUSWRTF0Ht_1IZ9Uz3TwquLRC4M99_ij3vsAU9VCzV8eyh60ord-8YNYaSjPlg0tjkSVRbKPj7oPbaJmPFFXji8IVmG9jRlqKLyL3vrlUE7fC9ldcIIjf4TEuDlxhcWM84Dwqlkls1YdsnJrYHZBUUgOWcphwf6VMzlmVpeGjN5dKrSA54XK-xvkR1_f7VXCaaiDfD21AyiazPyrCcFJbMCumWQerJVa29i86iRycs2lOt7Abi3d1l354Z-IMCtv56_gO4nHGrWK3tjQGdoiz8wW6bx8ySliMf9GUvtFxVjrMGBaU3GZyO244fXjQqtUAF8HauSfKKd97rU0Bxjn0W4Uvg-QfuKnqf-2toxtuQiLQSnJiZ24sEmvPMCK=w1284-h1713-no
 
Nice, that’s a IIe isn’t it? Quite busy in there, what are the cards?

I’ve got the disk card and an Epson printer card with mine. It also came with a third-party 64k 40/80 column board, but I think that is for an Apple III (the slot is longer, it won’t physically fit in the II Plus!).
 
Oh yes it’s a ][e, sorry about the confusion :)
Mouse card, serial card, printer card, Duo Disk card, Z80 card and graphic card (scart colour interface).
 
The Apple II’s colour capability was a very clever hack, but it was still a hack. Describing how it works would probably need a description of how analogue composite video works, which would need a description of what phase-modulation is, but Woz didn’t bother with that theory stuff, so I won’t: he just realised that if you sent a very fast-cycling bit pattern out of a composite video output, a colour monitor would interpret it as a solid colour. So, he played with the timing to get stable colours, and the result was Lo-res graphics. The reason the 16 colours are so oddly chosen is because that’s just what you get from the possible 4-bit patterns (actually, there are only 15 colours, as the grey#1 0101 and grey#2 1010 are identical). Doing it this way meant that the video output circuitry could be implemented entirely with digital logic, with no need for any additional chips. That’s another thing Woz was good at: super-minimal chip-count designs: he also did some crazy things with the display memory layout on the Apple II simply so that he could avoid a needing to include a DRAM refresh circuit - the layout of the screen is odd, but it ensured that every row of the RAM chips was accessed continuously simply because the display is constantly being generated...

It’s so skanky it’s beautiful.


Thank you @KrisW for the graphics explanation, it’s not the first time I’ve heard a commercial electronics design say, “well it works”
 
Nice machine there Tony.

For what it's worth, every Nait2 was made on a pick and place machine driven by Apple ][e workstations. All the programming was done on an app in CP/M so they had z80 cards, Microsoft Basic, TDS digitizer etc. The machine itself had a video card to view the PCB holes and make sure the components went in the right place. All very clever and in 32KB RAM IIRC.
 
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Cool, I didn’t know that! The Apple II certainly ended up in a lot of industrial and science scenarios as the architecture was so open and flexible. All manner of cards exist and many businesses made their own for all manner of niche roles, and I get the impression there are still a few ancient IIs earning their keep driving otherwise obsolete industrial kit.

It is one of the reasons I’m curious about it and want to learn a little more. Until this one landed I’d never even seen an Apple II in the flesh (unless there is one in the London Science Museum Computer exhibit). It is amazing to think it was five years earlier than the BBC Micro. The latter obviously more advanced in many ways, but not by that much. It is an interesting bit of kit and the construction seems really robust.

I’m still very much focused on fixing the Apple. I’ve nothing to run on it when that is done! I need to find whatever the equivalent of the MicroSPI SD card device I have stuffed in one of my BBC’s ports. That provides easy access to a ton of games etc. Basic should be in a ROM, so there is something to do without anything else!
 

As an interim/concurrent project I’ve just ordered the board (with pre-programmed chip attached) to build myself one of these chip-testers. It will make fault diagnosis so much easier as it can test pretty much all the RAM and logic chips in the various vintage computers I own, plus a lot more. Seems like a really cool and useful product. Not cheap once all the bits are ordered (I’m guessing around £160 or so complete), but between the Apple, the two BBCs, the two Spectrums and the Electron it will no doubt get some use! Looking forward to building it.
 
Excellent, thank you, there’s certainly some there I’ve not landed on yet.

PS This is a great half-hour overview of the II including some of Woz’s tricks regarding colour output and disc drives etc:


I’ve grabbed pdf copies of the manuals he refers to.
 
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Benny is horrified! This is by far the tattier or the two drives. It was in such a state I only viewed it as a spares unit, so gummed up the headblock was stuck etc, plus there is corrosion, the frint logo was in a right mess. As such I’ve gone for a much deeper strip-down here, but I think it will come back assuming the electronics are ok. The head looks decent, the rails have polished up nice and shiny etc. Obviously I’ll not be able to test either until I’ve got the computer working, but I had to do something as they were both dirtier than I’d have been prepared to put a disk in. The other one is actually very good. I needed nothing more than patience and a lot of cotton buds there, no need to disassemble the head tracks. Even with the full strip of drive #2 I don’t think I’ve done anything to upset the alignment, I’ve not gone near the stepper motor etc. Amazingly the drive belts seem ok!

I’ll post another pic once it is all back together...
 


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