[Coco] RS-232 Pak Back to Stock

[John E. Bielak]

On 4/3/2013 10:08 PM, Gene Heskett wrote:
> On Wednesday 03 April 2013 22:01:32 John E. Bielak did opine:
>
>> I picked up a deluxe RS-232 pak thats somewhat modified that I'm trying
>> to put back to stock.
>>
>> The changes:
>> - The ROM has been cut out
> Leave that as it, its far more useful w/o it.
Yes, that seems to be the overwhelming consensus... though I'll drop a 
socket in there anyway.


>> - The trace for pin 4 cartridge edge connector has been cut and there is
>> a wire going out to an external connecter
> That is the IRQ line, put it back AND if using an MPI, pull 3 of the 4
> pullup resistors from the 4 connectors pins 8, and jumper all pin 8's
> together.  No more missed incoming characters.  And doesn't need an
> external wire to get the IRQ into the coco when the slot select switch or
> logic isn't set to the slot the cart is in.

Thanks, the MPI IRQ, that makes sense of that external wire.

I haven't really used a MPI much, so forgive the noob question, but will 
jumping all the 8 pins potentially cause any conflicts/problems between 
other paks? (Drive, sound, other RS-232 based devices like the CoCoPak 
drive, etc.)


>> - There's a jumper between E1 and E2
>> - A jumper appears to have been removed from E3 and E4
> That doesn't ring any bells, consult the manual on that.
Nothing in the manuals that I can find yet.

 From looking at the board, The E1 pad connects connector pin 4 (IRQ) , 
through a resister, to pin 15 (VCC) of the 6511.  Jumping E1 & E2 also 
sends the IRQ directly into Pin 26 (IRQ) for the 6551.

Pads E3 & E4  connect  to cart pins 6 & 8 respectively. (Clock and 
CART).... looking at the solder job it looks like it may just have been 
the E4 pad that was mucked around with.


Thanks!
-John-