PC-DOS 1.10 and PCem v12

[mal.sh]

In my previous topic: PC-DOS 1.10 and PCem v11 - I got errors when I had tried to run the IBM PC with the memory size less than 640 KB. Today I decided to try the new version with IBM PC-DOS 1.10 again.

I used the same configuration and I got:


64 KB -> OK
128 KB -> OK
192 KB -> OK
256 KB -> OK
320 KB -> OK
384 KB -> OK
448 KB -> OK
512 KB -> OK
576 KB -> OK

Now it works fine. Well done!



Then I decided to check FORMAT and repeated the following steps:

1) I set the memory size equal to 640 KB;

2) I made another copy of PC-DOS 1.10 image file and I mounted the one to drive B;

3) Machine was reset via "Hard Reset";

4) It was rebooted successfully;

5) I tried to use the next command: FORMAT B:/1 - and I got that error again:




What's wrong again?

[omarsis81]

I'm not sure if it helps, but it works with MS-DOS 6.22

format.png (53.41 KiB) Viewed 21956 times

[mal.sh]

I'm not sure if it helps, but it works with MS-DOS 6.22

As I can see you used 180 KB floppy disk in it, whilst I used an original 160 KB PC-DOS 1.10 floppy image in drive A and its copy in drive B.
Originally IBM PC 5150 was equipped with 160 KB 5.25" disk drives (320 KB 5.25" later), but there are no such type of drives in PCEm.

[omarsis81]

I don't know much about the subject of the first IBM PC, but for what I just read on Wikipedia it seems that 160 kb drives and 180 kb drives are the SAME, just that MS DOS could write another sector per track making 160 floppies store 180 kb

Quote: "This meant that SSDD disks initially had a formatted capacity of 160 kB,[127] while DSDD disks had a capacity of 320 kB.[128] However, the DOS operating system was later updated to allow formatting the disks with nine sectors per track. This yielded a formatted capacity of 180 kB with SSDD disks/drives,[129] and 360 kB with DSDD disks/drives"

https://en.wikipedia.org/wiki/IBM_Perso ... _diskettes

[Battler]

Yes but FORMAT might be trying to format 180 kB by default, which will fail in PCem when a 160 kB image is loaded since the floppy emulation is designed to fail when trying to format with parameters different from those of the inserted image. Try adding /n:8 to the FORMAT parameters.

[mal.sh]

Yes but FORMAT might be trying to format 180 kB by default, which will fail in PCem when a 160 kB image is loaded since the floppy emulation is designed to fail when trying to format with parameters different from those of the inserted image.

I've just checked FORMAT in PCem v10.1. It works.

Try adding /n:8 to the FORMAT parameters.

There is no such option of FORMAT command in PC-DOS 1.10.

[mal.sh]

I don't know much about the subject of the first IBM PC, but for what I just read on Wikipedia it seems that 160 kb drives and 180 kb drives are the SAME, just that MS DOS could write another sector per track making 160 floppies store 180 kb

Quote: "This meant that SSDD disks initially had a formatted capacity of 160 kB,[127] while DSDD disks had a capacity of 320 kB.[128] However, the DOS operating system was later updated to allow formatting the disks with nine sectors per track. This yielded a formatted capacity of 180 kB with SSDD disks/drives,[129] and 360 kB with DSDD disks/drives"

https://en.wikipedia.org/wiki/IBM_Perso ... _diskettes

It supports only 160/320KB 5.25" diskette drive according to the official documentation of IBM PC Disk Operating System v1.10

[Battler]

Try FORMAT without /1 then.

[mal.sh]

Try FORMAT without /1 then.

Done. I've got the same error:

[omarsis81]

Do you have that option in your IBM DOS?
That should do the trick. If not, what options do you have?

format8.png (92.96 KiB) Viewed 21811 times

[mal.sh]

Do you have that option in your IBM DOS?
That should do the trick. If not, what options do you have?

There are only two options of FORMAT command in PC-DOS v1.10: /S and /1

As I said above PC-DOS v1.10 officially supports only 160/320KB 5.25" floppy drives

[omarsis81]

I hope it gets fixed someday!

[omarsis81]

Maybe floppy listing should be re-arranged with something link this:

5¼ -- SSDD -- 160kB/180kb
5¼ -- DSDD -- 320kB/360kB
5¼ ---DSHD -- 1.2mB

3½ -- DSDD -- 720kB
3½ -- HD -- 1.44mB
3½ -- ED -- 2.88mB

or list them with the unformatted capacity (eg. 2.0MB for the 3½ HD)

[mal.sh]

I hope it gets fixed someday!

But It works very well in PCem v10.1

[Battler]

- mal.sh: PCem v10.1 had less accurate floppy emulation that did not check for the validity of parameters (ie. if they match the currently inserted floppy) at all when formatting. Evidently PC-DOS 1.10 FORMAT.COM does not do something right when formatting the floppy, therefore getting an error in 10.1.

[ecksemmess]

- mal.sh: PCem v10.1 had less accurate floppy emulation that did not check for the validity of parameters (ie. if they match the currently inserted floppy) at all when formatting. Evidently PC-DOS 1.10 FORMAT.COM does not do something right when formatting the floppy, therefore getting an error in 10.1.

You mean "therefore getting an error in 12", right?

Anyway, I don't see how this can really be blamed on PC-DOS 1.10 FORMAT.COM. I mean, presumably, it doesn't fail like that on real hardware, right? So either there's a bug somewhere in the floppy emulation, or the floppy controller that PC-DOS 1.10 expects to see simply works differently than whichever one(s) we're emulating...

[mal.sh]

- mal.sh: PCem v10.1 had less accurate floppy emulation that did not check for the validity of parameters (ie. if they match the currently inserted floppy) at all when formatting. Evidently PC-DOS 1.10 FORMAT.COM does not do something right when formatting the floppy, therefore getting an error in 10.1.

Just LOL. Are you serious? )

[omarsis81]

ibm_pcdos_format.png (39.72 KiB) Viewed 21639 times

Well, it seems that it works...
Looks like you been using a 160/180 disk on PCem and forcing to format a single side.
It works fine if you just use a 320/360 disk and there you specify /1 the single side format.

[mal.sh]

ibm_pcdos_format.png

Well, it seems that it works...
Looks like you been using a 160/180 disk on PCem and forcing to format a single side.
It works fine if you just use a 320/360 disk and there you specify /1 the single side format.

1) I used an original copy of IBM PC DOS 1.10 which was equipped with 160KB 5.25" floppy diskettes.
2) As I said above I also used FORMAT command without /1 option and I got an error.
3) 320/360KB 5.25" floppy drives MUST to be fully compatible with 160/180KB floppy drives and MUST fully support 160/180KB diskettes.

[Battler]

Just LOL. Are you serious? )

I suggest you do some logging of what FDC commands get issued and with what parameters, you'll be surprised how these old DOS versions' tools do not always behave the way one would expect them to.

[omarsis81]

Just LOL. Are you serious? )

I suggest you do some logging of what FDC commands get issued and with what parameters, you'll be surprised how these old DOS versions' tools do not always behave the way one would expect them to.

Sure, but if it works on real hardware with that exact same piece of software, it should work on PCem too...

[Battler]

- omarsis81: Are you sure it does? Have you actually tested on a real IBM PC with the exact same BIOS and a 360 kB floppy drive and an actual 180 kB floppy (ie. one with no second side at all)?

[omarsis81]

- omarsis81: Are you sure it does? Have you actually tested on a real IBM PC with the exact same BIOS and a 360 kB floppy drive and an actual 180 kB floppy (ie. one with no second side at all)?

Not me, but I took for granted that "mal.sh" did.

[Battler]

If he did, then it would be nice if he made some kind of FDC tool that did exactly the same thing PC DOS 1.10 FORMAT.COM does, and logs everything read from and written to the FDC. That way we'd have the real FDC's behavior to compare with the emulated one, rather than having to guess what goes wrong.

[Battler]

I just did some logging... one of the FDC commands PC DOS 1.10 FORMAT.COM sends even with /1 parameter is this: 4D 05 02 08 50 F6 . That second byte being 05 is very telling. Bits 0 and 1 are drive select, in this case 01, ie. drive B:, and bit 2 is head select, in this case 1, so second side. Therefore, it indeed attempts to format the second side even with /1 set.

[omarsis81]

I just did some logging... one of the FDC commands PC DOS 1.10 FORMAT.COM sends even with /1 parameter is this: 4D 05 02 08 50 F6 . That second byte being 05 is very telling. Bits 0 and 1 are drive select, in this case 01, ie. drive B:, and bit 2 is head select, in this case 1, so second side. Therefore, it indeed attempts to format the second side even with /1 set.

Then, why I succeeded formatting a single sided disk in a 320/360 kb using the /1 parameter?

[Shadower]

Hi mal.sh:
Not so expert here speaking... but like you I am looking for the "perfect" emulator.
Just as you did I made a copy of the PC DOS 1.00 original disk image, inserted it in B: and formatted it to 160kB with FORMAT of PC DOS 1.00. Everything worked! Have you tried with 1.00 or only with 1.10?
PC DOS 1.00 seems to work... what do you think?

snip1.JPG (36.67 KiB) Viewed 21450 times

[mal.sh]

Hi mal.sh:
Not so expert here speaking... but like you I am looking for the "perfect" emulator.
Just as you did I made a copy of the PC DOS 1.00 original disk image, inserted it in B: and formatted it to 160kB with FORMAT of PC DOS 1.00. Everything worked! Have you tried with 1.00 or only with 1.10?
PC DOS 1.00 seems to work... what do you think?

Thanks for testing PC-DOS v1.00, but I tried only 1.10 version.

What was your PCEm's configuration for that test?

[mal.sh]

- omarsis81: Are you sure it does? Have you actually tested on a real IBM PC with the exact same BIOS and a 360 kB floppy drive and an actual 180 kB floppy (ie. one with no second side at all)?

Additionally, I've asked my acquaintance from another forum to make extra check on its original IBM PC 5150.

[mal.sh]

Hi mal.sh:
Not so expert here speaking... but like you I am looking for the "perfect" emulator.
Just as you did I made a copy of the PC DOS 1.00 original disk image, inserted it in B: and formatted it to 160kB with FORMAT of PC DOS 1.00. Everything worked! Have you tried with 1.00 or only with 1.10?
PC DOS 1.00 seems to work... what do you think?

Pardon for repost, but are you sure that the version of IBM PC-DOS was 1.00 ?
There is no /1 option of FORMAT command in PC-DOS v1.00 according to the official documentation of IBM PC Disk Operating System v1.00