The TRS-80 Journey Continues

Bill Gunshannon bill.gunshannon at
Thu May 5 17:49:08 CDT 2022

On 5/5/22 17:12, Fred Cisin via cctalk wrote:
> Double sided drives in 4P shouldn't require anything more than software 
> patches, to tell the OS (TRS-DOS, CP/M, etc.) that you have and want to 
> use the other side.
> The Model 3 and 4 disk controller (did the 4P use the same one??) 
> supports double sided and uses pin32 as side select (as deity intended).

Pretty much.

> Therefore, of course, using a drive that was jumpered for model 1 will 
> require removing the pin 32 jumper that model 1 used as DS3.

While I have Model I's I never got into the modification stuff.  Today
I prefer to use things like MISE and FreHD (which also has a problem,
need to get in touch with Ian).

> (includes model 3/4 FDC pinout)
> This includes the 300RPM jumpering for [SEVERAL VARIANTS OF] 55GFR:

Got that one.  But it seems to be mostly interested in making them
work on XT's.

> The links on it to TEAC maanuals seem to no longer be supported by Teac.

The TEAC docs are still available but, again, even they seem
mostly interested in what it takes to use them with XT's and AT's.

> To test the suspect drive, you could connect it to a PC; with DS1 
> jumpered (instead of DS0), it should work as a "180K" (single sided 
> "360K").

a PC with a floppy controller?  Wow, is that ever retro.


More information about the cctalk mailing list