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TEAC FD-55A-00-U / unkown jumper

haglebu

Experienced Member
Joined
Nov 22, 2018
Messages
123
Location
Germany, Lower-Saxony, Hildesheim
I have a jumper on my TEAC FD-55A-00-U (SS, DD, 40 Tracks, 48tpi) whose function I cannot assign. It is a 3-point jumper called DS and can be plugged into either (right) ST or (left) WT.

x----(x----x) DS
WT_____ST

I have not yet found this jumper in all the TEAC manuals I know of. I have ST jumpered ( ). When I switch to WT, the content of the floppy can still be displayed with DIR, but a text file, for example, can no longer be opened.

(My test PC is an IBM XT 5160 and the TEAC FD-55A works fine. No problems with reading, writing and formatting (180KB or 160KB))
 

haglebu

Experienced Member
Joined
Nov 22, 2018
Messages
123
Location
Germany, Lower-Saxony, Hildesheim
I formatted a completely new floppy (after coldboot) with the jumper WT set under PC-DOS 3.30 and noticed a very strange behavior:

1. FORMAT B: /1
- the parameter /1 is not supported any more! Why that?

2. FORMAT B:
- actually 80 tracks are formatted (with head 0 and 1); the stepper actually takes 80 steps! I watched it with my eyes.

Finally, of course, the error message appears: Unable to write BOOT. Invalid media or Track 0 bad - disk unusable. This is a TEAC Typ A (SS, 40 tracks, 48 tpi)!!!(https://retrocmp.de/fdd/teac/TEAC_FD-55_Brochure_Mar85.pdf
 

Chuck(G)

25k Member
Joined
Jan 11, 2007
Messages
39,424
Location
Pacific Northwest, USA
Teac used the same stepper on all of its 40 and 80 track drives. The 55A uses the same PCB as the 55E (80T, SS), so the jumper is useful.

You got the error because you were still trying to access the drive as if it were double-sided, which it's not. So the FATs couldn't be successfully written, or were over-written.

There was a discussion some years back about modifying FD55s for double-stepping on the CPC Wiki
 
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