On Tue, 24 Dec 2013, Fred Cisin wrote:
On Tue, 24 Dec 2013, Steven Hirsch wrote:
I'm attempting to convert a TRS-80 DMK image
to ImageDisk format in order
to write out a real floppy. The original was 80-track, DS, DD and indeed
the sdltrs emulator concurs and can catalog the image without incident.
The DMK2IMD utility converts it without complaint and reports:
80X6400 DSMD
250k data rate assumed
But, when I fire up IMD and write it out things stop after track 39 and
tell me that 2880 sectors have been written. That's the correct number of
sectors, but they should be spread over 80 tracks.
Clearly I'm missing something, but am not sure exactly what. The drive is
80-track DSQD and data rate is 250Kbps. I am not set for double-step and
imd believes (correctly) that the drive is an 80-track unit.
(I have also tried this with a more common 5.25" HD 1.2M drive - using
250k-->300k rate conversion - but the same thing happens)
WHAT disk format is it?
Stock TRS80 was neither DS nor QD.
Model 1 was originally SSSD 35 track/35 cylinder,
Model 3 was originally SSDD 40 track/40 cylinder,
there were NUMEROUS aftermarket setups for other formats, such as doubler
for double density on model 1, and most aftermarket OS's would support
double sided, and/or 96tpi 80 cylinder.
Sorry, left out the key detail: It was an LDOS 5.1.3 diskette, and is
definitely 96tpi 80-cylinder, DS, "QD" (I don't like that way of
describing an MFM 250Kbps format, but it seems to be relatively common
usage).
And, I mistyped: IMD is claiming that 1440 256-byte sectors are being
written. Consistent with the fact that it's truncating the write after
Track 39.
Could one or more of your tools be interpreting
"80 track" to mean 40
cylinder double sided? (not a stock format, either)
That is very possible. If it counts each side as a "track", then that is
indeed a count of 80. Problem is that the sdltrs emulator is reporting
the correct geometry when I mount the image.
I'll dig into the source for DMK2IMD and see exactly what "80X6400 DSMD"
means.
Merry Christmas!
Steve
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