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400k floppy drive glitchfest (flashing warning?)

cheesestraws

Well-known member
I have lubricated and cleaned it (though perhaps not as well as I should?) the heads are clean. Sony Test shows the stepper as correctly working. I wrote this disc on the machine itself and it verified OK. The machine boots fine from other floppy drives using this 2.0 image.
 

Nixontheknight

Well-known member
I have lubricated and cleaned it (though perhaps not as well as I should?) the heads are clean. Sony Test shows the stepper as correctly working. I wrote this disc on the machine itself and it verified OK. The machine boots fine from other floppy drives using this 2.0 image.
Maybe the drive itself is dead. Do you have any other 400k internal drives you can swap in?
 

cheesestraws

Well-known member
I have the same problem on macintosh ED without floppy drive)

That's extremely interesting; in my case it only happens when trying to boot off that one floppy drive. My other drive is fine.

Now, I thought it was reading garbled data from the floppy drive and the result was that, but perhaps it's actually reading code from a place where code isn't in the ROM (?) and the drive in my case is just kicking that off?
 

techknight

Well-known member
its acting like a memory out of bounds condition. like a pointer that got sent off into the weeds which just starts filling up memory with w/e, eventually hitting screen memory. So yeah, its not executing or reading the code properly.
 

ScutBoy

Well-known member
Agreed that seems more like a software problem than a hardware problem... unless there's some kind of glitch in the electronics of the drive itself...
 

cheesestraws

Well-known member
Well, it only happens with that one drive; other drives are OK, as is the Floppy Emu, so it's certainly something to do with that drive. It also doesn't always do precisely that, sometimes it wanders off into a different bit of memory, makes the Welcome To Macintosh spasm like that, then draw lines all over the screen and then ends up back at the 'not a system disc' icon. And very occasionally, and funniest of all, it plays loud farting noises for a while then does a good vapourwave visuals impression.

Theory time with cheesey [anyone want to write me a theme tune?]: This drive had issues stepping beyond certain tracks, and I have a feeling that something is off so that it isn't reading properly after a certain point on the disc; this will eventually prevent a function returning somewhere in the OS, because it will start running the function then be unable to read the bit that returns to caller, and thus ends up with execution wandering off into the depths of memory.

But it's funnier to claim that the drive is possessed.
 
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