Invalid Media Byte on 1.44M floppies

[jca]

I made several installations using 720K floppies using the micro8088 BIOS without any problem. Just to be sure that these images were fully supported I ran Scandisk and scanned all sectors. It works fine.
I tried to run Scandisk on a 1.44M floppy and got the error of Invalid Media Byte. Scandisk says it can fix it but if you try it breaks the FAT table. Not only that but you cannot reformat it.
I also tried to format unbroken 720K and 1.44M floppies but it is impossible as FORMAT thinks they are 360K floppies, overriding with /F does not work better.
This is not a major problem as you can read from them. Apparently writing on them does not work: some time ago I wrote files on a 1.44M image but did not test it. Today I did and trying to read what is on it gives Sector Not Found.

Conclusion: you can only read from 720K and 1.44M floppies. This is enough for normal use.

[Malor]

I'm not sure you could retrofit a 1.44MB controller to real XTs, either. I think the original BIOSes in those units simply couldn't cope with that many tracks and sectors on a floppy. But I'm not certain of that, my memories are quite fuzzy.

The Monotech NuXT claims high-density floppy support, so it's clearly possible. I went and looked at their ROM updates page, and it says this:

These files are provided for repairing or updating the BIOS on your NuXT v2.0. They contain Sergey Kiselev's 8088_BIOS Version 0.9.8 (https://github.com/skiselev/8088_bios/tree/master)

It is recommended to update from 0.9.7 to 0.9.8 if you use floppy drives, as it fixes some floppy issues.

[dmckean]

I'm not sure you could retrofit a 1.44MB controller to real XTs, either. I think the original BIOSes in those units simply couldn't cope with that many tracks and sectors on a floppy. But I'm not certain of that, my memories are quite fuzzy.

The Monotech NuXT claims high-density floppy support, so it's clearly possible. I went and looked at their ROM updates page, and it says this:

These files are provided for repairing or updating the BIOS on your NuXT v2.0. They contain Sergey Kiselev's 8088_BIOS Version 0.9.8 (https://github.com/skiselev/8088_bios/tree/master)

It is recommended to update from 0.9.7 to 0.9.8 if you use floppy drives, as it fixes some floppy issues.

You had to replace the FD controller in an XT if you wanted to use high density drives.

[jca]

Yes, the XT supported only 360K floppies. This is why I was sure that the micro8088 BIOS used voodoo to support 1.44M floppies.
My post was mainly to warn users that it reads perfectly well 1.44M and 720K floppies but nothing more.
Do not try to write on them, do not try to format them, use them just as read only media.

[Malor]

You had to replace the FD controller in an XT if you wanted to use high density drives.

Right, but do they provide their own BIOS update or something? Or was the XT able to handle big floppies natively, given the proper controller?

[jca]

https://minuszerodegrees.net/transfer/3 ... _drive.htm

[dmckean]

You had to replace the FD controller in an XT if you wanted to use high density drives.

Right, but do they provide their own BIOS update or something? Or was the XT able to handle big floppies natively, given the proper controller?

I think you had to run software to make it work.

[spark2k06]

Tested, I can't find any problem with it:

[jca]

You are right and I discovered the origin of the problem before seeing your post and for a totally different reason.
Suddenly I could not edit any file: the editor came up but the file never showed up and I had to reboot.
If I used the help command the help came up but the subject did not come up and I had to reboot.
The only thing I changed was this KB command in my autoexec.bat. I removed it and the problems disappeared.
After seeing your post I redid a fast test by formatting a 1.44M floppy and running Scandisk without any problem.
For the time being the KB command went to the trash.

[spark2k06]

You are right and I discovered the origin of the problem before seeing your post and for a totally different reason.
Suddenly I could not edit any file: the editor came up but the file never showed up and I had to reboot.
If I used the help command the help came up but the subject did not come up and I had to reboot.
The only thing I changed was this KB command in my autoexec.bat. I removed it and the problems disappeared.
After seeing your post I redid a fast test by formatting a 1.44M floppy and running Scandisk without any problem.
For the time being the KB command went to the trash.

Ok, but anyway, I don't understand. Which KB command makes the script stop working? It doesn't make much sense.

[jca]

I had a better look at the KEYB command using HELP. It must be in the CONFIG.SYS using INSTALL, I had it in AUTOEXEC.BAT. I will test it tomorrow or more exactly later on today.

[spark2k06]

I had a better look at the KEYB command using HELP. It must be in the CONFIG.SYS using INSTALL, I had it in AUTOEXEC.BAT. I will test it tomorrow or more exactly later on today.

Agreed, but as I comment here, I find no link between the two:

viewtopic.php?p=65462#p65462

[jca]

Yes, it does not make sense that the KEYB command would have such an effect. It must be a symptom of something else wrong, likely in CONFIG.SYS.
Case closed:
1.44M and 720K floppies work perfectly well under the micro8088 BIOS.