8250 DiskDrive don't work

By igal

Master (217)

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05-11-2012, 15:54


Can you help me.

In BASIC, if i make FILES with a DSK inserted, my DiskDrive Led Flash and never stop that.
The motor turn slow and the head dont move.

If i start the MSX with a DSK inside the drive, i have a bleue screen and the BASIC never coming.

I have change the DiskDrive => The problème dont change.
I have change the CI 2793 in IC 153. the problème dont change.

Where IC need to change for this problème please?

Thank you for help Wink


By bennyroger

Expert (74)

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05-11-2012, 16:45

Check power supply, diskrom, disc controller.

By RetroTechie

Paragon (1563)

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05-11-2012, 20:39

Igal, have you tried with another disk? What happens when you boot the MSX without a floppy in the drive? What happens when that works, you insert disk (after booting without) and then do "FILES" ? And what happens when you hold [SHIFT] pressed during boot?

Other than that, it could be that the floppy drive itself has died. Being an electro-mechanical device, I'd suspect that first rather than the FDC. Another option (besides many other possibilities) is that system software is in EPROM & bits have started to 'leak'. EPROMs were used in many 8250/55/80 machines.

And indeed check power supply first (+5 and +12V, it's probably safe to ignore the -12V supply)

By Manuel

Ascended (19683)

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05-11-2012, 22:17

He already said he changed the disk drive, without results.

By RetroTechie

Paragon (1563)

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05-11-2012, 22:42

Oops I missed that... Tongue

Btw. could be a simple cabling problem, where the drive is started and then the FDC waits for some signal that never comes. For example I've seen floppy drives that would happily write to a write-protected floppy, because the "write protected!" signal didn't get passed to the FDC correctly. So you might want to measure the cable connections (multimeter, low resistance range, measure from a point on the 8250's mobo -> point on the floppy drive's controller board, so you catch everything in between). Or plug in another 8250 floppy cable & see if that fixes the problem.

Floppy cables are usually reliable enough, but remember there's 4 contacts per signal (mobo pin -> plug, plug -> wire, wire -> plug on the other end, that plug -> floppy drive pin). And at least a dozen signals passing over the same cable.

By msxholder

Champion (399)

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05-11-2012, 23:48

Is it an msx original drive or pc drive 720 versus 1.44
That can make a difference (sure!!)