[net.micro.6809] 80-track drives for free?

knudsen@ihnss.UUCP (03/15/84)

I heard at a Coco club meeting that the stepper motors in RS disk
drives (and presumably all others) are actually geared twice as fine
as required for 35/40 tracks.  That is, they are pulsed TWICE to go
to the next track.  So, some copy-protection schemes use "half-tracking"
where they write between the regular tracks.  (Ever notice the funny
sound that Sands of Egypt makes when it boots up?  SOunds like double-
speed stepping, all right).
	Now, does anyone know how to make the Coco step half of a normal
track (one step) at a time?  Could this be trusted as an 80-track device?
(probably not, as tracks may be too wide on the medium).  --mike k

jlw@ariel.UUCP (03/15/84)

I doubt that the Sands of Egypt or other copy protected software
                     on COCO
uses half track stepping^. I have a pair of Qume 1978 vintage SSDD 40
trackers on my COCO and it works fine.

<FLAME ON>

My copy of ZAXXON crapped out this week.  I HATE copy and backup
protection schemes!!!!!!!!

<FLAME OFF>



					Joseph L. Wood, III
					AT&T Information Systems
					Laboratories, Holmdel
					(201) 834-3759
					ariel!jlw

glen@intelca.UUCP (Glen Shires) (03/16/84)

Unfortunately, just because you can get a 40-track drive to half-step
between tracks, you can't use all 80 tracks.  This is because the 
disk drive head will read/write tracks that are too wide.

Yes, some software uses the intermediate half-tracks for copy
protection, but they then never use either of the normal tracks on
either side of the half track.  (All used portions of tracks are always
atleast a full track apart).

The color computer is not the only machine with software driven
stepping motors that allow half-tracking, the apple ][ does too.

^ ^     Glen Shires, Intel, Santa Clara, Ca.
O O     {pur-ee,hplabs,ucbvax!amd70}!intelca!glen
 >
\-/    --- stay mellow