I've got an Apple IIe that had started to misbehave, culminating with it giving up entirely.
It had been working fine. I'd previously swapped out the keyboard Rom as that had given up the ghost, and there had also been an issue with the PAL encoder chip (the name of which escapes me now, but was a swap out replacement).
I had it out today as part of an exhibition, and it had been sitting there running Pac-Man. I noticed the machine had hung and restarted it. No problem, it came right back up, but after a while it stopped again.
The crashes became more frequent with less time between restart and hanging. Then, one reboot resulted in a screen full of inverted @ symbols and no startup beep. The subsequent reboot was fine but crashed very quickly, and now the @s are all I get.
Doing a Control-SolidApple gave me
IOU FLAG: 1 2 3 4 5 8
but sometimes I get different numbers (into the hex digits on some occasions).
In desperation I did remove the IOU chip, gave it a good squirt of contact cleaner and then reseated the chip, but it made no difference.
Is this likely to be the IOU? Any advice would be welcome.
All the best,
Paul
Thankfully we are on the cusp of a time when there will be newly made FPGA based replacements for the IOU and MMU chips for the //e. For a long time those have basically been "unubtanium". Since they haven't been made since the early 1990s and new old stock of them dried up years ago the only source for replacements was donor motherboards, which aren't that common. If you search here on AppleFritter though you will find that the project to develop a replacement is very close to being completed and the parts available. Probably only a few months out from being able to order them, probably from ReActive Micro.
I received a package on Monday containing FPGA based replacements for both the MMU and IOU chips.
Initial testing is that they work great! I'm super excited!
Not sure how far these are from being available to order, but this is going to offer a new lease on life for a lot of //e units with bad chips.
It also opens up the possibility that new //e motherboards and complete new //e units will be possible to build with mostly all newly manufactured parts. For the first time in over 30 years, the //e could be back in production.
Would you check them with larger, well populated RAMWorks vintage card, and possibly with more peripheral cards in the slots?
I have tested them with a vintage "Super Expander" which is a Taiwan clone of the original RAMworks card with 512MB and a 512MB add-on card. I have a repro Mockingboard in slot 4, a Dan ][ in slot 5 and a Disk ][ controller in slot 6. I can try adding a couple more cards. Alexandre and Ralle have asked me to test with a variety of hardware which I have.
This sounds all very promising!
Meanwhile, I managed to find a "working but bad RAM" IIe motherboard on ebay. Apple 8-bit machines were comparatively rare in the UK - we were all Sinclair, Acorn and Commodore - and on the basis parts don't come up too often I bit the bullet and bought it. Bit steep at £130 but, like I said, they are like gold dust over here.
I do like a story with a happy ending:
PXL_20250709_154730580.jpg
But if the FPGA replacement parts come out soon, maybe I can bring this donor board back from the dead too...
We're very close to these adapters be available to order, and I think it's more weeks away than months away. The testing phase is pretty advanced and shows that so far, these adapters work perfectly. On the other hand, I don't want to rush anything -- we've been waiting for IOU/MMU substitutes for 30 years, what's a couple of weeks more? I don't want to face the nightmare of discovering a problem and having to figure out a way to upgrade the firmware of all adapters that has been sold.
Back in january, Ralle Palaveev offered me his help in designing the adapters. It’s been quite a ride: full of highs, dead ends, letdowns, and moments of absolute triumph. I'd like to write a post on how it all went, but I'm about as slow writer as you can get. I'll probably stick to a summary. But the gist of it is that we originally wanted to use the Lattice iCE40. We had lots of problems with it due to the low number of GPIOs, the lack of space on the board, and it's slow configuration speed. At some point, we decided to abandon this FPGA and use the MACHXO2 instead. That forced us to throw away our design and start anew. Then we had weird things happening while experimenting with the IC we planned to use for voltage level-shifting (the LSF0108). We had to use this IC when we used the iCE40 (there weren't enough GPIOs for direction signals). We didn't have this limitation with the MACHXO2, so we decided to re-design (again!) to use the 74LVC245.
The designs for the IOU/MMU substitutes are completely open-source and is located here:
IOU: https://github.com/frozen-signal/Apple_IIe_IOU_3V3
MMU: https://github.com/frozen-signal/Apple_IIe_MMU_3V3
And the firmware is here: https://github.com/frozen-signal/Apple_IIe_MMU_IOU
I personally won't sell these, and I won't make any profit or other form of compensation from them. I feel I owe so much to the Apple IIe that I view this as returning a favor. I know Ralle will start selling them soon, and that ReActiveMicro should sell them as well.