[TUHS] Disk data layout (was: /dev/drum)

[hellwig.geisse@mni.thm.de (Hellwig Geisse)]

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On Mi, 2018-04-25 at 11:31 +1000, Greg 'groggy' Lehey wrote:
> 
> But by itself that's not overly convincing.  I looked at the manual
> for the IBM 3330, but I couldn't find anything specific.  Does anybody
> else have any useful reference?
> 

I kept the manual of the first hard disk drive that
I ever integrated into a microcomputer system. This
was a Shugart SA600 Fixed Disk Drive; the OEM manual
is Copyright 1981. It had the (then) common 5.25" form
factor, and could store 8 Mbytes on non-replaceable
platters with 6 surfaces.

Figure 2-4 in the manual shows the disk surface.
"TRK 000" is the outermost track, "TRK 159" the
innermost one. Even closer to the spindle is the
"Head Shipping Zone" on "TRK 182", which could be
accessed by a regular seek.

Finally, section 4.4.1 explicitly states that the
interface signal "Track 00" is true only when "the
read/write heads of the selected drive are at track 00
(the outermost track)".

Hellwig