Pretty sure it's not a SA-800 problem, that was just something we tried in the course
of running out of other ideas. These controllers are meant to talk to SA-460 or Tandon
TM100-4 96tpi 300 RPM drives ("quad density").
I did of course force head loading on drive select, which does make the SA-800s load the
heads when selected. Still nothing written to the diskette, though.
I'm sure the SA-800s are good as they're my main test bench drives. They've
been extra-special-exactly aligned so I can interchange media with Mike Douglas' FDC+
Altair compatible disk controller, which has very strict index timing demands.
Coincidentally, these are the drives I bought from you, Bill, when you moved out of the
Wilmington building! The ones that had the locked steppers.
??????? Original Message ???????
On Thursday, August 12th, 2021 at 11:39, Bill Degnan via cctalk <cctalk at
I would think Herb would have some valuable input, but
I do know with the
SA800's there are a lot of jumpers, they vary based on the rev of the
board, and you want to be sure that the loading of the heads is not jumper
dependent. NOTING that I am only being logical not technical. I would
only look to cross jumpering related to the drive head control off the list
of possible causes.
On Thu, Aug 12, 2021 at 11:26 AM Jonathan Chapman via cctalk <
cctalk at classiccmp.org> wrote:
> Does anyone have experience running the MTI MXV22M? It's a dual-height
> QBus card that emulates RX02 but uses a 5.25" 96 TPI drive. I've got a
> small heap of them and we're trying to get them going.
> When trying to format diskettes using the process documented in the
> manual, the drive selects for maybe a second then deselects, and we get a
> drive not ready error. The controller isn't using the ready line, as the
> SA-460 for which it is designed doesn't supply it. No traces physically
> connect to pin 34.
> Since we're close to out of ideas, we've also plugged in a pair of Shugart
> SA-800s, on the idea that maybe the MXV22M is close enough to the MXV22 to
> show some signs of life. It doesn't give a drive not ready error, and it
> will step the heads like it's really formatting, but never loads the heads.
> Happy for any input on this one!