29 Oct
1999
29 Oct
'99
10:42 a.m.
John wrote:
He also mentioned he has source code on 8 inch disks
from an
Ohio Scientific, Inc. machine. He thought hed have more trouble
finding a way to read those because of its scheme of using an
6820 parallel port controller and a 6850 serial port controller
to access floppies. Is that true? Should the normal scheme for
connecting a Shugart-y drive to an old AT-era WD controller
work to read these old disks?
He's right. Ohio Scientific used a UART as a disk controller. I haven't
looked at the schematics, so I'm not sure what method they used to avoid
long runs without flux transitions; maybe they really could tolerate nine
zeros (a start bit and eight data bits) between ones (stop bits).
Anyhow, the only way I know to read those disks is to use the actual
Ohio Scientific hardware. If that couldn't be done, I think I could hack
together something with a Scenix microcontroller.
Eric