The Teac FD-55GFR is a 96tpi drive.?? It can replace a 55G (1.2M), or a 55F
(720K) depending on controller, but it still has a narrow head for doing 80
tracks.???? It will have to be jumpered to run at 300RPM, not 360.
On Thu, 5 May 2022, Bill Gunshannon via cctalk wrote:
It has a jumper that leave that up to the controller.
But, the TRS-80 controller doesn't implement that signal; if the default
of signal not present is 300 RPM, then it's all set, . . .
I used double sided as far back as my first Model III. Even had a
full height Tandon 80 track double sided drive. All I ever needed
was DOSPLUS or NEWDOS80.
That would be the Tandon TM100-4
Although TRS-DOS didn't (until 6.0?, when TRS-DOS became rebranded LDOS),
the after-market OS's supported DS and 80 track.
I don't remember how you needed to tell the OS that you had DS or 80
track.
But, once the OS knows, then the 55GFR, operating as a 55F, can, of
course work.
Do you know how to tell your CP/M about DS and 80 track?
https://www.tim-mann.org/trs80faq.html#[19]
Discusses the drive selects and Mentions that you can use 55GFR, but
doesn't give the details that you need?? (300/360 RPM, double stepping,
etc.)
The 4P has the missing pins. I never liked it and usually end out
putting in real cables and using Drive Select like it was intended.
At least until IBM won and the started making 3.5" drives without
any way to do drive select.
Good. The TRS-80 and IBM special cables were specifically because they
didn't think that their own staff, and customers, could set drive-select
properly on the drives.
But, more importantly, is the fault ONLY when format/verify?
Does it still READ disks that you already have?
Haven't really tried that. Most of the disks I have are over
20 years old. If it fails to read who's fault is it? The drive
or the disk.
But, if it WORKS, . . .
One more possibility to pay attention, (you probably already know this, so
sorry if saying it offends you), ...
You need to use 300 Oerstedt ("360K") diskettes.?? If you use 600 Oersted
(1.2M) disks, they will seem to work, and then immediately, or VERY soon,
lose their content.
Yeah, I knew about that. I still have piles of real floppies laying
around. :-)
The college purchasing agent was in bed with a supplier, and kept getting
us Roytype HIGH DENSITY disks for our TRS-80 lab. Even when we explicitly
said not to substitute.
