3.5" Altair CP/M

[Chuck Guzis]

On 3 Jun 2007 at 13:11, Grant Stockly wrote:

>> TARBELL MINI-FLOPPY DIAGNOSTIC OF 8-1-80
> STANDARD VERSION 1.8
> 40 TRACKS    18 SECTORS
> 
> What I would really like to do is find some way of connecting a 3.5" disk 
> drive to the MITS hard sectored controller card set.  This would give me 
> the 300 or so K and allow me to run MITS basic off of the disk.  Do you 
> know anything about how to do that?  Is it possible?  Maybe with a PLD to 
> deal with soft/hard sectored stuff?

So I was pretty close.  The 1771 is keeping 128 byte sectors--which 
figures.  IIRC, the MITS controller required an 8" drive.  Just 
confugure a 1.44M as an 8" SS soft-sectored drive, use 26x128x77 
format and enjoy the 250K that it brings you.

Yes, you could generate index pulses with something like a PIC (you'd 
want to adjust the spacing to conform to the drive speed).  But the 
50K additional is, IMOHO, not worth it.

Cheers,
Chuck









> 
> I have not investigated anything yet so I am not sure what it would 
> take.  If its possible I'm sure I could get it done.
> 
> Grant 
> 
>