[Coco] coco1 - 26-3003A

[Bruce W. Calkins]

In the era of the CoCo 1 64k chips were just coming off the lines.  It was 
expected that some of the chips would be "half good" and could be sorted to 
upper half good and lower half good.  The "E" board CoCo had provision for 
upper bank or lower bank "32k" chips.  By the time 64k chips were readily 
available the half good idea pretty much fizzled out as there were not 
enough half good chips to make them worth keeping out of the recycling bins.



As a result, most CoCo 1s with 32k of memory are actually 64k machines. 
However the upper bank may need to be enabled with some wiring to a spare 
gate on the 74LS02.  The last version (283 board?) of CoCo 1 did include the 
circuitry for full 64k operation.



All "32k" CoCo 2s were full 64k machines, with the exception of any CoCo 1 & 
2s with piggybacked 16k chips for 32k upgrades.



Bruce W.



====================================



----- Original Message ----- 

From: "Benoit Bleau"

> If I recall, there were no such things as 32K rams, they really were 64K (
> unless they were 2 banks of 16K rams piggy-backed on top of each other).
>
> If this board is an E board, you would need to modify it to correctly use
> the 64K.  It was a very simple modification to do. Look for Frank's 
> Tandy's
> little wonder book, it should be in there.
>
> -Benoit.
>
>
> On Tue, Nov 6, 2012 at 12:35 PM, Charlie <chazbeenhad at hotmail.com> wrote:
>
>> Thanks for the reply!
>>
>> I was hoping it was 64K.
>>

>>
>> Charlie