[Coco] modpack hack was Re: Drivewire question

[Darren A]

On 3/26/09, Willard Goosey  wrote:
> On Thu, Mar 26, 2009 at 01:58:20PM -0700, Darren A wrote:
>> Conversion from Modem Pak to Serial Pak usually includes changing the
>> address decoding from the range used by a Modem Pak (FF6C - FF6F) to
>> the range used by a Serial Pak (FF68 - FF6B). I think this involves
>> running the A2 address line through an inverter before going to the
>> CS0 input on the 6551.
>
> Ehh, maybe.  Like I said, I gotta spend some quality time with the
> data books, and Dr. Goodman's instructions.   Just looking at this
> half-hacked board is going to give me a headache.
>

I just took a glance at Dr Goodman's document about the CoCo Pro
serial pak. The schematic does show an inverter on the A2 line with
the note: "Added Gate". It appears to use previously unused gate 'A'
(pins 1 and 2) of the 74LS04.

Darren