Hi, I have a 512K Mac with an odd floppy drive related problem. I've narrowed it down to the mainboard by swapping parts around between another perfect 512K system.
The floppy drive will read, but it won't write. If I use a Floppy Emu instead, same issue with a floppy image file I boot from. If I put the Floppy Emu in HD20 mode it sticks up an error code, whether I start with a 3.2 disc with the HD20 enabler and normal ROMs or with Rominator ROMs installed. The Floppy Emu in HD20 mode works fine with other 512K and Plus systems.
I'm now thinking the IWM floppy chip has something wrong with it or perhaps it's one of the filter chips near the port? What does everyone else think? What would you socket first? I've got a Mac Plus board that I'm planning to use as a donor, as the chips all look the same for the floppy circuit parts.
It otherwise works normally if I boot from the Rominator, but the floppy drive issue is still there.
Update 10th April - I socketed the IWM chips in a Plus and the 512K and swapped them over. The Mac Plus still writes to a floppy with no issue. The 512K booted from the Floppy Emu in HD20 mode, so I thought it was fixed... Then tried an external 800k drive along with Rominator bootup and got the same old error when trying to save from Macwrite to floppy, "bus error" I think. Then tried the Floppy Emu in HD20 mode again and this time it hung with an error. Urgh!
Will try swapping the floppy port filter chip next. Could be some small part that's only needed when writing to floppy port?
The floppy drive will read, but it won't write. If I use a Floppy Emu instead, same issue with a floppy image file I boot from. If I put the Floppy Emu in HD20 mode it sticks up an error code, whether I start with a 3.2 disc with the HD20 enabler and normal ROMs or with Rominator ROMs installed. The Floppy Emu in HD20 mode works fine with other 512K and Plus systems.
I'm now thinking the IWM floppy chip has something wrong with it or perhaps it's one of the filter chips near the port? What does everyone else think? What would you socket first? I've got a Mac Plus board that I'm planning to use as a donor, as the chips all look the same for the floppy circuit parts.
It otherwise works normally if I boot from the Rominator, but the floppy drive issue is still there.
Update 10th April - I socketed the IWM chips in a Plus and the 512K and swapped them over. The Mac Plus still writes to a floppy with no issue. The 512K booted from the Floppy Emu in HD20 mode, so I thought it was fixed... Then tried an external 800k drive along with Rominator bootup and got the same old error when trying to save from Macwrite to floppy, "bus error" I think. Then tried the Floppy Emu in HD20 mode again and this time it hung with an error. Urgh!
Will try swapping the floppy port filter chip next. Could be some small part that's only needed when writing to floppy port?
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