[comp.sys.tandy] Color Computer 1/2 + Disk Drive

cccph@jessica.cs.ucla.edu (Charles Hobbs) (05/21/91)

I have two 16K Color Computers, a Coco 1, and a Coco 2. Initially, the
Coco 1 had Extended Basic, the Coco 2 did not. I also have the
Color Disk Controller, and one disk drive.

For a while, I was using the disk drive with the Coco 1. But, I wanted
to take advantage of the nicer keyboard on the Coco 2. Since the
Disk Controller requires Extended Basic to operate, I pulled the
Extended Basic ROM from the Coco 1 and put it in the Coco 2.

The Extended Basic works fine in the Coco 2. When I plugged the
Disk Controller into the Coco 2, with Extended Basic, the system
boots up into Disk Extended Basic, but the disk doesn't operate
at all. (I've checked the cable, and it's installed properly.)
DIR, FREE(0), DSKINI 0....all that happens is the disk will spin
for a while....and then ?IO ERROR.

Ok, is there something in the Coco 2 that I am forgetting about?
Thanks in advance....

____________________________________________________________________
|Charles P. Hobbs           | BBC micro, Aquarius and Spectravideo
|cccph@jessica.cad.ucla.edu | users! Please email me! Thanks!
|Ham radio: N6YMK           | L.A. Blue Line Freq: 471.3375 mHz

ww0n+@andrew.cmu.edu (Walter Lloyd Wimer III) (05/21/91)

Your disk controller is probably one of the older Tandy models which
required +12v in addition to +5v.  The CoCo 1 supplied +12v but the CoCo
2 and 3 do not.  You need to do one of the following:

1.)  Get a Multipak Interface (I think all the Tandy models supply +12v,
but I'm not entirely sure).  Multipaks are rather difficult to find. 
You might find a used one for sale, or maybe a third-party version (make
sure it supplies the +12v).

2.)  Get a newer disk controller which does not require +12v.

3.)  Hack your drive and controller to get the +12v from the drive power
supply.  This is what I did in order to run my old controller in my CoCo
3; it worked fine.  Make sure you tap off the regulated side of the
power supply.  You also have to turn on the drive first, then the
computer (the WD1793 disk controller chip requires the +12v to come up
either before or at the same time as +5v).

4.)  Hack your CoCo 2 to supply +12v.

5.)  Use some kind of external +12v power supply.  This and (4) are
pretty similar since you'll probably need many of the same components
(transformer, rectifiers, filter capacitors, voltage regulator).


Good luck,

Walt Wimer

jimomura@lsuc.on.ca (Jim Omura) (05/22/91)

In article <2819@lee.SEAS.UCLA.EDU> cccph@jessica.cs.ucla.edu (Charles Hobbs) writes:
>
>
>I have two 16K Color Computers, a Coco 1, and a Coco 2. Initially, the
>Coco 1 had Extended Basic, the Coco 2 did not. I also have the
>Color Disk Controller, and one disk drive.
>
>For a while, I was using the disk drive with the Coco 1. But, I wanted
>to take advantage of the nicer keyboard on the Coco 2. Since the
>Disk Controller requires Extended Basic to operate, I pulled the
>Extended Basic ROM from the Coco 1 and put it in the Coco 2.
>
>The Extended Basic works fine in the Coco 2. When I plugged the
>Disk Controller into the Coco 2, with Extended Basic, the system
>boots up into Disk Extended Basic, but the disk doesn't operate
>at all. (I've checked the cable, and it's installed properly.)
>DIR, FREE(0), DSKINI 0....all that happens is the disk will spin
>for a while....and then ?IO ERROR.
>
>Ok, is there something in the Coco 2 that I am forgetting about?
>Thanks in advance....

     The original CoCo supplied both 5 volts and 12 volts to the
controller.  The CoCo2 only supplies the 5 volt line.  You'll either
have to change controllers to a newer version or add the 12 volt
line(s).  I don't have my manuals handy but it's clearly set out
in the buss definition where you have to add the 12 volts.  Actually,
you could probably pick up a 2nd hand controller cheap if you can
find someone who moved up to the no-HALT type disk controllers.


     Say, I noticed you seem to have a Spectravideo.  I wish I
had one of those again.  They were really nice.  I still have
a Yamaha CX-5MII (MSX) computer, among other things.
-- 
Jim Omura, 2A King George's Drive, Toronto, (416) 652-3880
lsuc!jimomura
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