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

From: Francesco Messineo <*francesco.messineo_at_gmail.com*> Date: Thu, 11 Jan 2024 14:08:34 +0100 Message-ID: <CAESs-_wHxJcicVcuj7z-+ziembQV2qsgR496HuS9_hc9eteOfw_at_mail.gmail.com> · francesco.messineo_at_gmail.com

On Thu, Jan 11, 2024 at 2:03 PM Francesco Messineo
<francesco.messineo_at_gmail.com> wrote:
>
> On Thu, Jan 11, 2024 at 1:58 PM Santo Nucifora <santo.nucifora_at_gmail.com> wrote:
> >
> > Just to clarify:
> >
> > The 8250/SFD-1001 uses a Matsushita JU-570 or JU-570-2 drive mech.  The C900 uses a JA-560-012 drive mech and the serial number on mine is in the 100s.  I have never seen another drive in the wild.  Other than the C900 documentation, I have not been able to find any other info on these drives.
>
> according to this document:
> https://retrocmp.de/fdd/panasonic/Panasonic_JU-475-4_Service_Manual_OCR.pdf
> The JA-560 is a 96 TPI drive
Ok maybe this can be indeed a too quick conclusion, the -012
additional part number may indicate a different head actuator that
makes it a 100 TPI drive. Indeed there seems to be no documentation
about these drives. I would just try to find information about the
disk format, 80 VS 77 tracks would clarify the issue.
Frank