[Coco] 1.2 MEG DRIVES might be ot

[Gene Heskett]

On Sunday 16 July 2006 17:39, Phill Harvey-Smith wrote:
>George's Coco Address wrote:
>> Dave,
>>
>> Isn't a 1.2meg drive an odd size? I thought they went from 720K to
>> 1.44meg. Can they work with a Coco?
>
>1.2MB drives where 80 track, double sided 15x512byte sectors per
> track, as used on the IBM AT. On the AT they could also read the 360K
> 40 track drives by double stepping the heads.
>
>As with 1.44MB drives they may be usable on the CoCo/Dragon in double
>density mode, as 80 track drive giving 720K/disk.

That will be if the jumper that slows them down to 300 rpm can be found, 
by default they spin at 360 rpm.  Once thats done however, they make 
great DSDD 720K drives (I have one such here) that can also *read 40 
track disks.  However, it takes the same jumper speed slowdown to make 
them work with the 40 track disks also.

That about speed being said, there were some aftermarket controllers 
that used the fujitsu 8877 fdc chip, and a determined experimentor 
could convert one of those to handle the 500kilobaud data rate just as 
easily as with the original 12 volt only controller.  Just follow the 
basic outline of the instructions for the 12 volt model.

>Phill.
>
>--
>Phill Harvey-Smith, Programmer, Hardware hacker, and general eccentric
> !
>
>"You can twist perceptions, but reality won't budge" -- Rush.

*don't ever write to a 40 track disk in one of these, the disks data 
will be forever trashed when then loaded into a 40 track drive.

-- 
Cheers, Gene
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Copyright 2006 by Maurice Eugene Heskett, all rights reserved.