Apple II+ Restoration

Background

I have an Apple IIe Platinum that works great, but I was worried some of my crazier demos won't work on older hardware. How could I test this?

Then I remembered that back in the early 90s my high school was throwing out all of their old Apple II gear (for ugly IBM PS/2 Model 25). I snagged some of the equipment they were getting rid of, and it's followed me around for years, across moves to many different states.

I didn't have a case (I think I thought it was too bulky? or maybe all of the ones left were broken?) so I don't know what the serial number was, but the chips all have late 1982 datecodes so this is a relatively late II+ model.

I can't remember if the motherboard was in working condition when I originally got it.

Running Development Log

8 August 2018

Got the parts out of "storage", really just thrown into a cardboard box full of cables with some newspaper padding. Not ideal.

I have one power supply, one keyboard, and two motherboards. One is in much better shape than the other. The worse one is missing a lot of chips, though I think I still have them somewhere (I harvested it for the 74LS logic chips).


18 August 2018

I was off on a trip, but had ordered some parts on e-bay before I left. So now I have a case and Disk ][. I also ordered a Mockingboard and power-supply rebuild kit from Reactivemicro.


20 August 2018

The power supply powered up, no magic smoke escaping. The voltages were all vaguely in range so I thought I'd live dangerously and try firing things up.


I don't have the proper mounting hardware, so you see it's lifted up on spare 1.25" standoffs from my Raspberry Pi Cluster.

It was a pain trying to get a monitor next to it that could take composite in. I ordered a small security monitor but it hasn't arrived yet. I'm temporarily using a composite to VGA scan converter I have which doesn't do that great with colors.

Anyway fired it up... and nothing. I had the keyboard connector in backwards. Oops. That might have cost me a 74LS04. Put the cable in properly and now the power light comes on, but the display shows this pattern, blinking with a solid white screen. No beep. Hmmm. I guess it's time to start investigating.


21 August 2018

Well, I thought next I'd update the old power supply (a 605-5073) with one of the Universal ones from ReactiveMicro. They claim it should take like 15 minutes.

Apple pretty strongly doesn't want you opening that case.


The lid wouldn't come off... would you look at that, it's got some rivets holding things on. That wasn't in the directions, but you can find forum posts about this kind of thing.


I could drill out the rivets, but of course on hand I only have an old-style hand-drill. It worked though.


The inside. I hope there are some bleeder resistors on there. It does appear to be an Astec model. The capacitors all look more or less OK, but probably makes sense to swap things out.


I had a lot of trouble getting the strain relief off. Thought I'd check some of the related videos. Look, there's one from my partner in team Pluto in the $6502 challenge at KFEST18.


His video wasn't much help though, it kept skipping over the hard parts with cuts. Anyway eventually did rotate the strain relief and get it open:


And I got the board out. The bottom, if anyone is curious:


Time to put the new board in. To make things confusing instead of brown/blue or black/red wires for the AC, mine had red/blue, but I think I got everything hooked up right. It was really hard pushing the wires into the connector. And the yellow wire for the DC wasn't quite long enough so I had to move the strain relief up about 0.25" so I hope it will still reach the motherboard OK.


Powered it up, and the voltages looked more or less right, so tried it out. The II+ still isn't booting, but you'll notice the glitches in the screen went away. Not sure if that's co-incidence or not.


Anyway, needless to say this all took more than 15 minutes.

22 August 2018

Thought the next step would be to reseat some chips. The pins all look nice and clean, but then I noticed something about the 6502:


It was inserted *backwards*. How could that even happen? Though now I dimly remember that 20+ years ago I might have assembled this board out of the remains of 2-3 non-working boards.

Figured I had nothing to lose and flipped it the right way around, and possibly it's at least still partly working. It beeps and the keyboard moves the cursor... but the cursor is a blinking solid black square on a white background. Odd. I don't think it's an issue with the new composite monitor that finally arrived.


22 August 2018 -- continued

I think I found out why the text generation wasn't working:


Why would both of the motherboards I have be missing the ROM SPCL character generator chip? Now to see if I can find a replacement. I think it's EPROM compatible so I could just burn one, but that assumes I have access to an EPROM burner.

It does seem like the machine is working though. The keyboard turns out to have issues, but if I manage to type "GR" then "VTAB 1" you can see that lo-res is working (not sure why I'm not getting color though).


27 August 2018

Well some packages came in! The standoffs were most important, but while I was at it I got some spare 6502 chips plus a bunch of 74LS chips as backups. Sorry for whoever at digikey who had to wrap up one or two each of like 20 different chips.


Connected the power supply and put in the standoffs. I somehow forgot to get aluminum 6-32 screws so the back row is going to have to be held on with nested standoffs.


And everything installed:


Even though I got the EPROM programmer, still don't have any 2716 yet. But I do have some programs that don't need text mode, so let's try them.

Setting up the Disk II. I carefully installed the connector, knowing my bad habit of installing things backward.


This disk actually has my KFEST18 demo on it. The disk drive was quieter than expected and makes more horrible grinding noises than I like, but it did load successfully.


Black and white still though. Is it this cheap display?


So I got the composite->vga converter out again, and did get color, but horribly wrong color. This converter works OK on my IIe so wonder where the problem is. The trim pot doesn't seem to help much.

I did put in the Mockingboard too though, and music is working fine.


Comparison of the colors, and what the color should look like.


28 August 2018

Thought I'd try to troubleshoot the lack of color, as I had tested the display on the IIe and it worked fine there.

First let's see if the 14MHz clock is in range. I have to admit I wouldn't know one way or another from just looking at the signal, but it's nice to use the oscilloscope for something.


Then the 1982 Apple II Repair manual does have an issue for "no color" and it gives some chips to try. I didn't have a spare 74LS11, but did have the others, and sure enough swapping out the 74LS02 in B13 fixed the color issue! Colors look nice, I couldn't get the screen to photograph well.


The 74LS02 in question, from 1982. Though I didn't double check it was really dead, it might have been OK and just needed to be re-seated.


30 August 2018

I had ordered some 2716 EPROMs as well as some compatible EEPROMs. The EEPROMs got here first, though I had to wait a bit in the morning as the mailman was running later than normal. The packaging left a bit to be desired (no padding or anti-static foam at all, just shoved in an envelope).


Time to try out the new EPROM programmer. It's a MiniPRO TL866CS, and yes I'm programming from Linux.


The ROMS read out fine (I read out their contents first to be sure) but they wouldn't program. They are both supposedly AT28C16, but if you look on the underside they have different markings and one looks a lot more worn than a 2017 date code would suggest.

So maybe they are counterfeit? I did get them on ebay as I had trouble finding them at a reputable supplier. After a bit of research and guessing they did program fine as CAT28C16A chips (5-volt only chips). Not sure why you'd remark a CAT28C16A as an AT28C16 though.

And when inserting the first one managed to break a leg off. Did get the second one in fine.


And it booted!


The keyboard has been questionable but after hitting each key 50 times, all of the keys are at least partially working.


30 August 2018 -- continued

Time to do some real tests. Got to open the floppy disks I got as a prize at Kansasfest18. "For Governmenal and Educational use only". Well, I suppose this has all been rather educational.


And it turns out you can't type underscore on an Apple II+ keyboard. Oops, I've been making some poor filename choices. Though that complex CHR$(95) command did work.


Ran the diagnostic... and oh no, memory error in bank 2. I guess that's hardly surprising.


And yes, you can see it pretty obviously if you do anything with HGR page2 at $4000 (16k).


You can actually hear the stuck bit in my CREDITS demo. The mockingboard data is loaded to that memory range, and the music plays in a minor key. Odd.

4 September 2018

The EPROMs arrived a bit too late to be useful. Though nice to have a backup in case the EEPROMs have issues. They do look cool though:


Anyway the spare motherboard I have had a few 4116 RAM chips on it, so tried swapping them in and out and eventually found the bad chip. Now HGR2 works!


Time to put everything back together! One holdup was I didn't have any screws for attaching the keyboard to the case. It turns out they are the same black case screws as under the front of the keyboard. So I used those on the keyboard, and used some extra 6-32 standoffs to attach the case front, which looks odd but works for now.

Anyway firing up the demos! But not all of them worked. I was worried for a bit, but it turns out to be an issue with the interrupt handler. The machines before the IIe-enhanced had much simpler firmware interrupt handling, so I had to go back and make all my code save X and Y plus get A from $45 before they worked.

But everything seems to be working now:


Back to my Apple II stuff