3.5" Altair CP/M

[Chuck Guzis]

 On 5/15/07, Grant Stockly <grant at stockly.com> wrote:
> I have a tarbell floppy controller card that has been rewired to access
> 3.5" disks using a standard PC 3.5" disk drive.  I have 3 disks that the
> Altair can boot off of and read, but my windows computer can't do anything
> with them.  I've tried rawread.exe and diskinfo.exe and they both choke on
> the disk.  I assumed that if a disk could be written with the standard 3.5"
> disk drive on the tarbell card then it should also be read on the same
> drive connected to a modern IBM compatible.

Without more information, the best anyone can do is try to read your 
mind.

Here's my try.

You're putting an 8" format on a 3.5" drive.  Perhaps the drive 
you're using uses pin 2 as a density select and completely ignores 
the extra HD hole in your 720K  disk. 

That's sort of the opposite of recording a 720K format on a 1.44M 
disk--the cure there is to cover the HD hole in the 1.44M disk.  If 
the reverse were true, you'd drill (or punch) a hole in the 720K 
floppy.

Cheers,
Chuck