100 v 96 (was: Tandon TM-100-4M curiosity

Christian Corti cc at corti-net.de
Mon Aug 13 04:42:02 CDT 2007

On Fri, 10 Aug 2007, Fred Cisin wrote:
>> at least I could
>> perfectly read all my SORD M23 disks in a standard DSHD drive (with tracks
>> 0-2 obviously missing at the beginning). The M23 disks are 100tpi SS MFM,
>> the drives used are TEAC FD-50C.

> All of the Sord disks that I've seen have been 96tpi.

Hm, what SORD disks? There were modern SORDs like the M68K and the newer 
version of the M243 that had standard 5.25" drives, they were low profile 
desktop machines from the mid-80s. The SORD M23 is from 1982, the external 
FDD is a SORD FD-20 that contains two TEAC drives.
I must admit that I had't tried to read *all* tracks, I had only read 
some random tracks across the disk with AnaDisk. I've just done a SCAN of 
the disk now. It starts with a difference of three tracks (track 0 is read 
with track ID 3 and so on) and finishes with a difference of six tracks 
(track 73, track ID 79). There are three areas where the drive sees some 
sectors of one track and some of the next track (e.g. at track 42 it sees 
sectors from track 46 and from track 47), partially with read errors.
BTW the disks are single-sided, MFM, 16 sectors/track (1-16), 80 tracks,
interleave 2:1.


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