29 Apr
2011
29 Apr
'11
8:25 p.m.
On Sat, 30 Apr 2011, Philip Pemberton wrote:
18/256 looks more likely.
The head-zero tracks all have far more than 9 sectors on them. With so
many sectors it's hard to tell, but 18 seems plausible based on the
inter-sector gaps.
Those 9/512 sectors look suspiciously like DOS 360K tracks... though
what I don't get is why every track is formatted like that. DOS 360K is
only 40 tracks. Unless it was read in a 40-track drive..?
40 track Single sided drives were standard in TRS80. If a disk was
formatted PC360K, and then RE-formatted on TRS80, then you would have 18 x
256 on side 0 and 9 x 412 on side B
Model 1 was sssd 35 cylinder 10 x 256 (cf. Osborne SD)
aftermarket DD
Model 3 SSDD 40 cylinder 18 x 256
aftermarket CP/M and other mods, DS, 80 cylinder, etc.
some of the aftermarket CP/M mods used a variety of different disk formats
Model 4
same as model 3, but 80 x 24 video, memory mappable to 64K contiguous
CP/M 3.0 available from Radio Shack (8? x 512), but didn't catch on
Model 4P
same as model 4, in a Compaq like luggable case
Never expect a TRS80 disk to be adequately labeled as to what it is.
LOTS of "EVERYBODY uses Dos-Plus", "NOBODY uses TRS-DOS", etc.
--
Grumpy Ol' Fred cisin at xenosoft.com