Creating new CP/M disks - Progress on IMSAI
cclist at sydex.com
Sat Jan 12 11:37:06 CST 2008
> Date: Fri, 11 Jan 2008 23:50:27 -0500
> From: "Richard A. Cini" <rcini at optonline.net>
> Anyway, one of the issues I have with the Teac FD-55GFR (1.2mb
> high-density; no schematic) drives Im using is that the motor runs all of
> the time (just like an 8 drive) but these late-model Teac drives dont
> have head relays, so the heads are engaged all of the time.
Since the 8272/765 does drive "polling", you have to connect DRIVE
SELECT/ to DRIVE SELECT/. Connecting it to MOTOR ON/ would likely
have some odd effects. Recall also, that the 765 can do overlapped
seeks on multiple drives, which requires that the DRIVE SELECT/ line
be what it says it is.
Which leaves you with connecting HEAD LOAD/ to MOTOR ON/; not a good
solution if you do a lot of multiple-drive operation (as CP/M floppy
systems are wont to do). Better would be to use a timer to monitor
the HEAD LOAD/ line and keep MOTOR ON/ active for a minute or so
after the last drive activity. A (or a couple) of NE555's should do
Recall that with the 55GFR, as the drive will not gate INDEX/ pulses
until it's determined that the diskette's come up to speed. (This,
BTW, is why hard-sector diskettes don't work in a 55GFR). So if
you'r getting INDEX/ pulses, the drive, by definition, is ready.
That's not to say that you couldn't get a GFR with a head-load
solenoid, but they're pretty uncommon.
My take anyway.
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