If you have access to a Gimix SS-50 6809 or 6800 system, Gimix used the
WD1791 in their double density disk controller. That controller can do
single and double density 5 1/2" and 8" disks (250KHz, 500KHz & 1MHz
data rates).
On 5/17/2023 2:38 PM, Fred Cisin via cctalk wrote:
As for the target machine having a serial port, one of the machines I
want to get stuff onto is an Osborne 1A. The serial port on that is
horrible.
On Wed, 17 May 2023, Robert Feldman via cctalk wrote:
For CP/M computers such as the Osborne, you can read and write their
diskettes on an MS-DOS computer with a program like Media Master.
KayPro disks are harder, as there are problems formatting them on an
MS-DOS computer.
The earliest Osbornes were single density with ten 256 byte sectors
per track. I was able to write some code on TRS80 model 1 to read those.
Many PC FDCs, including the IBM 5150/5160, can not do FM/single-density.
Then Osborne came out with a "double density upgrade". The
MFM/Double-density Osborne disks are easy to do with PC, if you are
familiar with INT13h and INT1Eh.
But, my original stock 5150 PC could never read the original/early
Osborne disks.
Single sided Kaypro disks were not hard to do. Nothing special, other
than smaller than ideal inter-sector gaps to squeeze ten 512 byte
sectors per track.
But, the double sided Kaypro disks had an incorrect value in the head
number field of the sector headers of the second side! The WD
controller used in the Kaypro ignored that field, but the NEC FDC
insisted on a match. I tried some double-sided Kaypros, and found
that they would work fine with disks that had the correct value in the
head number field. So, I could format the disks in Kaypro double
sided format on the PC, then copy files to those pseudo Kaypro disks
on the Kaypro, and bring themback to the PC to read.
--
Grumpy Ol' Fred ci...@xenosoft.com
