[Coco] PAL Coco 1/2 schematics/timings

[Little John]

Here's some info on memory upgrades:
http://www.gimechip.com/pages/Tandy Radio Shack TRS-80 Color Computer Memory 
Upgrade FAQ.html
It is something my son started, but has yet to finish....
if the link doesn't work, you can find it at:
http://www.gimechip.com/pages

----- Original Message ----- 
From: "Aaron Banerjee" <spam_proof at verizon.net>
To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
Sent: Saturday, September 18, 2010 7:54 AM
Subject: Re: [Coco] PAL Coco 1/2 schematics/timings


>I believe it was the "285" board that was the same as the "F" board.   I 
>upgraded one once to 64K.  Aside from the chips, I only remember  having to 
>clip a few capacitors in the memory area.
>
> Regarding 4K "D" boards, I've got one that's been upgraded.  It is  quite 
> flaky, but I'm not sure if that's just because it's old, or that  you have 
> to dink with them in order to use the 32/64 K and that the  "surgery" was 
> only 95% successful.  I'd like to keep it running --  especially since it 
> still has the "4K RAM" sticker on it....
>
>      - Aaron
>
> On Sep 18, 2010, at 8:29 AM, Bruce W. Calkins wrote:
>
>>> Mark,
>>>
>>> I have Schematics / Service Manuals for most of the European PAL  boards 
>>> (starting with one of the first 4K PAL CoCo 1 from 1980/81  or so 
>>> (serial #3xx, wasn't that named an "F-Board"?)
>> <snip>
>>>
>>> Best regards,
>>> Torsten
>>
>> No, the "F" or 283 board was the last version of the CoCo 1 and had  a 
>> lower limit of 16k, with hardware provisions for 64k accessable  with 
>> OS-9.  4k would have been a "D" or earlier board.  The "E"  board had no 
>> provisions for 4k, but required added wireing for 64k.   Few "C" or 
>> earlier boards were released for sale, so data on them is  limited.
>>
>> Bruce W.
>>
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>
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