Bug? Strange behaviour with floppy images and Amstrad keys

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Zup
Posts: 40
Joined: Mon 30 Nov, 2015 10:47 am

Bug? Strange behaviour with floppy images and Amstrad keys

Postby Zup » Mon 22 Aug, 2016 1:12 pm

I've got some (screwed up) disk images and I was trying to fix them. The images were 1474560 bytes long (= 80x2x18) but they were formatted as 720k (=80x2x9).

To fix them (store as 737280 bytes images, same disk format as declared) I set up a ami486 machine with two disk drives. The first one was a 1440k (I was reusing an older machine) and the second one was a 720k one. Both drives are defined on BIOS with the same settings. I put the original file on disk drive A and a formatted 720Kb disk image on drive B.

I let MS-DOS (6.22) start and use DISKCOPY A: B: to copy the disk. Diskcopy found original disk as 80x2x9 (OK), but was unable to copy the disk. I tried to (re)format the image on B: but said that track 0 was damaged (even using /U /F:720 switches).

The disk images were from a spanish Sinclair PC200, so I set up another machine (this time a PC200) but I left the same settings (A: 1440, B: 720) by mistake. Diskcopy (this time MS-DOS 3.20) and format didn't work. Then, I corrected the mistake (A: and B: 720k, but disk images were 1.44Mb and 720Kb) and MS-DOS was capable of copying the disks without problems.

Trying the same configuration on the ami486 (=both drives 720Kb) worked as well. So it seems that MS-DOS is unable to copy disks or format if the two floppy drives have different specs. I don't know if that happens on real life as well (I had not any computer with two floppy drives), and it's good that PCem allows that image files mismatch (putting a 1.44Mb image file on a 720Kb disk drive).

BTW, there is some kind of fault on Amstrad keyboard controllers. When I was working with Amstrad PC2086 (PCem v10) I found that keyboard was unreliable and often failed after using some keys (mostly characters like á or CTRL or ALT key combos). Copying that disks I find that sometimes CTRL key gets "stuck" after doing CTRL+END (to go to the menus). Pressing CTRL to change key status don't work. It only happened to me with Amstrad machines (PC2086, Sinclair PC200) so I guess it's related to their keyboard controllers (their keyboard weren't XT compatible).

Are Amstrad PC1512 joysticks emulated? They were connected using a DE9 connector on the keyboard and it seems that they generated scancodes. I guess that "emulate" that should be as easy as using joytokey to generate keypresses on PCem, but I wondered if they could be supported (or if they already have any support).
Battler
Posts: 793
Joined: Sun 06 Jul, 2014 7:05 pm

Re: Bug? Strange behaviour with floppy images and Amstrad ke

Postby Battler » Mon 22 Aug, 2016 3:58 pm

Zup wrote:I tried to (re)format the image on B: but said that track 0 was damaged (even using /U /F:720 switches).

That's the intended behavior. If the FDC emulation thinks you're trying to format a floppy to a different format from the original, it aborts with a sector not found error.
Zup
Posts: 40
Joined: Mon 30 Nov, 2015 10:47 am

Re: Bug? Strange behaviour with floppy images and Amstrad ke

Postby Zup » Tue 23 Aug, 2016 6:07 am

But floppy B: was defined as 720k on PCem, BIOS and the disk image (737280 bytes, with DOS format). If both A: and B: are defined as 720k it works, but if A: is defined as 1.44Mb and B: is defined as 720Kb, formatting B: won't work.

I forgot to mention: I'm using "vanilla" PCem v11, not any testing release.

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