[Coco] mpi upgrade

[Nuxie at aol.com]

Here is a document i found in my paper archives this might or might not  help 
you. Here it is anyway. 
 
 
Purpose: to eliminate dual addressing and insure proper operation with  color 
computer 3.
 
DISCUSSION:  Currently the main data buffer in the Multi Pak is  enabled with 
I/O access to address in the range of &HFF40 through  &HFF40.  It is only 
necessary to enable this buffer for the range of  addresses from &HFF40 through 
&HFF7F. The color computer 3 uses  registers located in the range of addresses 
from &HFF80 through &HFF9F  which could cause a conflict with the Multi Pak 
unless this range is disabled in  the Multi Pak's address decoding.  This will 
be done by installing a new  PAL on the 26-3024 Multi Pak. or by installing a 
satellite board on the 26-3124  Multi Pak. 
 
PROCEDURE: 
If you are modifying a 26-3024 Multi Pak, perform part A below. 
If you are modifying a 26-3124, perform part B below
 
PART A: 26-3024
 
1. Remove the PAL at IC location U8 and replace it with a new IFL ordered  
under part number listed below. 
                    IFL, 82s153     part#AXX-7123  Catalog# 26-3024
 
2.  Test the Multi Pak by installing a cartridge in each slot,  plugging it 
into a color computer, and insuring each cartrige slot can be  accessed by 
setting the front panel switch to that slot's number.
 
PART B: 26-3124
 
1.  Order a satellite board kit with the part number given  below.  The kit 
will contain a satellite board with 7 wires attached, a  plastic spacer and a 
3/4 #4 screw.
 
         Satellite board part #  AXX-7119  cataloge# 26-3124
2. with power removed, remove the four screws holding the top case to the  
unit.  Be sure to note the length of the screws as to their location.   Remove 
the top case. 
 
3.  Remove the three screws holdig the logic board to the bottom case,  
leaving the transformer connected.  remove all the metal cliips holding the  shield 
to the bottom of the PCB, noting their positions.  Remove the  shield.  This 
is to avoid melting through the shield insulation while  soldering. 
 
4.  Cut the trace coming from pin 52  of IC6 that connects pin 52  of IC6 to 
pin 19 of IC1.
 
5.  Position the satellite board over IC6, cocomponents up, with the  wires 
facing towards the card edge connector which plugs into the color  computer. 
 
6. connect the 3 yellow wires to IC4 pins 3, 9, and 11.  Any order is  fine. 
 
7. connect the white wire to IC6 pin 52, taking care not to short the leads  
of IC6
 
8. connect the blue wire to IC! pin 19.
 
9.  connect the black wire to IC5 pin 8.
 
10 connect the red wire to IC5 pin 16.
 
11. replace the shield and two of the logic board screw, the one near the  
power switch , and the one near the selector switch.
 
 
that's all i had wrote down on that but i am assuming the next step is to  
test it or something. 
 
Hope this helps in a small way.....
 
Mary Kramer



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