Re: Reading Commodore 900 disks in the 8250 (LP)

From: Michal Pleban <*lists_at_michau.name*> Date: Thu, 11 Jan 2024 13:01:59 +0100 Message-ID: <58883e47-86cc-e6a6-9de1-1bd2d1f72cb8_at_michau.name> · lists_at_michau.name

Hello!

Francesco Messineo wrote on 10.01.2024 16:45:

> according to this page
> https://www.zimmers.net/cbmpics/c900.html
> The 900 has a 96 tpi floppy drive, the 8250 has (for sure) 100 tpi
> drives.

I am not entirely sure that this info is correct (see how it also says 
it's 1.2 MB whereas the disks have in fact 1.0 MB capacity). I do know 
that the disk drive interface is identical to the one used in the 
8250LP. The C900 documentation states that MFM support is incomplete, 
and only GCR is used in the disk controller code, so they would not need 
to bother with 96 TPI MFM disks. The C900 mech is also outwardly 
identical to the one from the 8250LP except it has a grey faceplate, so 
I think there's good chance it is simply the same 100 TPI mech.

Regards,
Michau.