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Apple IIgs Possible bad IWM?

VERAULT

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I have a Rom 01 Apple IIgs which passes all onboard as well as disk diagnostics. However whenever I have a 5.25" Floppy drive connected (both unidisk or std 5.25" Floppy drive) it spins indefinitely and the drive LED stays on forever. IT will boot and read disks, but the drive never stops nor does the light go out. I have tried 4 known good drives. Is this a failing IWM chip?
 

Chuck(G)

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Given that the drive motor enable ENBL1/ENBL2 comes right out of the IWM without buffering to the floppy, I'd say that it's a pretty safe bet that your IWM has issues.

However, consult this thread before pulling out your soldering iron! It could be your cable.
 

VERAULT

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Given that the drive motor enable ENBL1/ENBL2 comes right out of the IWM without buffering to the floppy, I'd say that it's a pretty safe bet that your IWM has issues.

However, consult this thread before pulling out your soldering iron! It could be your cable.
Thanks Chuck,, but which thread?
 

VERAULT

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So I pulled the IWM off my Donor board (IIGS rom 03 with a failing diagnostics I have never been able to repair pertaining to the SERIAL interface) and swapped SMD chips. The rom 01 IIGs now behaves as normal. I put the faulty IWM on the donor board and its behaving the same... Drive always on LED always on but still can read disks.

So where can I purchase a replacement IWM chip? Any ideas?

IMG_20230316_172024.jpg
 

resman

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You can always just pop a standard Disk II card in slot 6 and set it to My Card in the setup
 

HoJoPo

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Mac SE 800k motherboard should have an IWM in the correct form factor, if you find one with battery damage. The FDHD motherboard / SE/30 board will have the 1.44MB capable SWIM (Super Wozniak Integrated Machine) instead. The SE ones might be socketed, as an upgrade to FDHD was a ROM set/SIMM and a chip if I remember correctly.

I've used a Disk ][ interface on a IIgs before, in fact that's the way my IIgs developer seed prototype came, with a Disk ][ controller and drive.

It does look like there have been efforts to replace IWM with an FPGA, but 5V FPGAs are getting hard to come by, so a logic level converter is required. https://www.bigmessowires.com/2018/01/31/yellowstone-cloning-the-apple-ii-liron/
 

VERAULT

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Mac SE 800k motherboard should have an IWM in the correct form factor, if you find one with battery damage. The FDHD motherboard / SE/30 board will have the 1.44MB capable SWIM (Super Wozniak Integrated Machine) instead. The SE ones might be socketed, as an upgrade to FDHD was a ROM set/SIMM and a chip if I remember correctly.

I've used a Disk ][ interface on a IIgs before, in fact that's the way my IIgs developer seed prototype came, with a Disk ][ controller and drive.

It does look like there have been efforts to replace IWM with an FPGA, but 5V FPGAs are getting hard to come by, so a logic level converter is required. https://www.bigmessowires.com/2018/01/31/yellowstone-cloning-the-apple-ii-liron/
A mac se board wouldnt be too hard. I have done an SE to SE FDHD I replaced the ROM, I dont remember replacing the IWM...

An FPGA replacement sounds interesting I need to look into that.
 

HoJoPo

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A mac se board wouldnt be too hard. I have done an SE to SE FDHD I replaced the ROM, I dont remember replacing the IWM...

An FPGA replacement sounds interesting I need to look into that.
Looks like the SE uses the 28 pin DIP IWM like the Liron, not the PLCC IWM like the IIgs. So they wouldn't be directly compatible, you'd have to have a 28 pin to PLCC adapter built. That's probably why you remember replacing ROMs, there were 2 ROM chips and a 28 pin DIP IWM in the SE FDHD upgrade kit.
The SWIM (Super Wozniak Integrated Machine, 1.44mb capable IWM successor) chip is used in a PLCC package on the SE/30 and on other models, but I don't know if it would work with the IIgs ROMs.
There is a discussion on 68kmla about IWM chips here: https://68kmla.org/bb/index.php?threads/source-for-iwm-chips.7341/
 

VERAULT

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Well I went through my bad boards and all I have is:
apple 344s0061-a swim X2
apple 343S1069-a ???
apple 343S1060-a ???

I cant find much on the last two (they are on the same board but I dont think they would be any good either)
 

bladamson

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When I was trying to find and IWM for a ROM3 board, I came to the conclusion that the IIgs IWM is its own special thing, and that none of the mac ones will swap with it. I may be wrong, but I was never able to locate anything else with a compatible IWM.

I'd get one of the BMOW Liron clones and drop it in slot 6, if I were me.
 

VERAULT

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When I was trying to find and IWM for a ROM3 board, I came to the conclusion that the IIgs IWM is its own special thing, and that none of the mac ones will swap with it. I may be wrong, but I was never able to locate anything else with a compatible IWM.

I'd get one of the BMOW Liron clones and drop it in slot 6, if I were me.
If thats the case then that really stinks!
 

bladamson

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I've got one with 2 or 3 of the pins corroded off from battery acid if you want it (and I can figure out which dead parts jar I threw it in). I was going to try to mill into the body to where I could solder on fly wires, but eventually just got disgusted and bought a cheap ROM3 with a busted up case and swapped boards.
 

VERAULT

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I've got one with 2 or 3 of the pins corroded off from battery acid if you want it (and I can figure out which dead parts jar I threw it in). I was going to try to mill into the body to where I could solder on fly wires, but eventually just got disgusted and bought a cheap ROM3 with a busted up case and swapped boards.
haha man you are on! Challenge accepted..
 

VERAULT

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I've got one with 2 or 3 of the pins corroded off from battery acid if you want it (and I can figure out which dead parts jar I threw it in). I was going to try to mill into the body to where I could solder on fly wires, but eventually just got disgusted and bought a cheap ROM3 with a busted up case and swapped boards.
Send me a pm and Ill send you postage.,
 
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