Upgrade processor to 08BSPE2T or later

Original processor boards 08BSPDT (8088) and earlier variants are mostly pin compatible with the newer 08BSPE2T (also 08BSPET and 08BSPE1T) boards.  But, some wires changed on the input connector.  The processor boards after 08BSPET need 12 vdc supplied to MTA 39 pin2 to power the inputs on MTA 38 and 39. In addition some machines may require programming key inputs on 2 wires to 2 inputs. Read the rest of the article to see why.

Also see the implementation notes on a 08BSPE3T processor if using this board.  08BSPE3T Processor Board release notes

Without the 12 VDC connected, the inputs on the processor will not work and may read 0 vdc at the input rather than 12 vdc when not made.   

MTA 38 was a 10 pin connector on 8088 boards and on 80186 boards this is now a 6 pin connector.  MTA 39 was a 6 pin connector and is now a 8 pin connector on 80186 boards.  So, you may need connectors to make the conversion.  
 

DIsplay Compatibility

Machines with 2 x 20 displays may also need to change the display to a later version.  The 08BSEVFD5U display may have to update to 08BSEFVD5V due to a communication baud rate updates. This may be as easy as a jumper fix on the display.

08BSEVFD5V is shown in the picture.  The 08BSEVFD5U has the jumper made at J0.  You can cut the jumper or solder a jumper as needed for the differing versions.  

 

The story behind MTA 39-2 and 3

There are 2 banks of protected ram.  This is why you might need both MTA 38-2 and 3 jumpered together.  .  

On machine like single stage presses, MTA 38-3 is used for the ram full prox input. So, do not jumper MTA 38-2 and 38-3. Any machine that uses MTA 38-3 for an input other than a programming key should not jump MTA 38 -2 to 3.  

Washer extractors (and possibly other machines that require more ram) require the jumper from 38-2 to 38-3.  Programmable outputs caused the need for the extra ram space in the washer extractor.  

Wire changes

Old processor	New processor
MTA38-2	MTA38-1                             SIGNAL CANCEL
MTA38-3	MTA38-2 & 3 (see notes)          PROGRAM KEY
	MTA39-2   +12VDC               DC power for inputs