16 Mar
2014
16 Mar
'14
11:49 a.m.
On Sun, 16 Mar 2014, Chuck Guzis wrote:
On 03/16/2014 09:44 AM, Steven Hirsch wrote:
80-trk, 9 x 512-byte sectors per track, single-sided, 300kbps MFM. This
was in a 1.2M Teac HD drive.
I probably stated the rpm figures bass-ackwards above. Point is, the Teac
FD-50 drive can read even tracks properly when seeking to them from at
least 10 tracks away, but single stepping puts me into la-la land.
If I had the data rates screwed up, I wouldn't expect the FD-50 to read
anything anywhere, much less be able to pick up all sectors on the "good"
tracks.
Do you have any thoughts about the stepping issue - that's my real
concern.
Steve
--
I'm hoping someone can shed light on this. I
picked up a couple of NOS
Teac FD-50A-03 floppy drives with DEC badges on the front and have been
trying to use them in various older systems with little success.
Yesterday I sat down with ImageDisk on my duplicating machine and
started digging deeper. These things are behaving very oddly. From
what I read on the web, the FD-50A-03 is a single-sided, 96tpi drive
that supports 250KB/sec data rate and spins at a conventional 360rpm.
This seems nominally to be true, but...
No, the FD-50A spins at 300 RPM, which is conventional for "360K" drives.
Treat it as a single-sided 55F.
I created a reference diskette by formatting
single-sided on a known
good 1.2M drive at 300K/sec (to account for its 300rpm operation). This
should be the correct layout for the Teac drive. Here's where things
get weird:
Again, you've got it backwards. The conventional "1.2M" dual-density PC
drive spins at 360 RPM (just like its 8" big brothers). There are, of
course, dual-speed jumper settings on most of these old drives, so that
250Kbps data is handled at 300 RPM and 500kps data is handled at 360K, but I
don't think that's a problem ehre.
- If I configure IMD to treat this as an 80-track
drive and tell it to
read the reference diskette single-stepped, it can read even numbered
tracks only. The odd number tracks all throw read errors.
Exactly how did you format the test disk? That is, what parameters did you
use?