[Coco] 8" drive to 5.25" replacement?

[Gene Heskett]

On Tuesday 02 December 2003 23:53, Roger Taylor wrote:
>Someone wrote me about a worn out 8" drive on a machine they use and
> wanted to emulate it by connecting the cable to their PC... :)
>
>I told them it might be best to try to replace the drive with an
> older 5.25" drive that can do single-density mode.  What I wanted
> to ask you guys is if the cables are compatible between 8" and
> 5.25" drives.
>
>thx
>
>{Roger Taylor}

Not in the ones I've seen Roger.  But my experience is a bit limited 
to a pair of early Shugart 810's in a character generator we once 
used.  The CG had an interface chip in the 1793 family, but the 
cables were split and dupped a bit, using a 50 pin header connector 
like a scsi.  I don't think they were near all used, but there were 
some tweaks available that we never had in the 5.25" drives too.  
Zone control of recording drive for instance.

Note that the 1.2 meg 5.25" drives like the teac-55G are basicly this 
8" drive in a smaller package, and with doubled track density.  The 
drive speed is cranked up to 360 rpm, with a 500 kilohertz data rate, 
at which point it looks electrically exactly like the older 850 
drives but with 2x the tracks.

But, the 1793 is the only one in that chip family that can do 500khz, 
the rest are limited to 250khz, the std coco data rate.  Slow that 
drive down to 300 rpm with a jumper setting and its a 720k drive for 
a coco.  Or 765kb if you want to play with the descriptor, adding a 
track at a time till it won't format the last one, then back off by 
one.  That was 85 tracks I got on this one.

-- 
Cheers, Gene
AMD K6-III at 500mhz 320M
Athlon1600XP at 1400mhz  512M
99.27% setiathome rank, not too shabby for a WV hillbilly
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by Gene Heskett are:
Copyright 2003 by Maurice Eugene Heskett, all rights reserved.