80 Series Newbie

[Paul Berger (Canada)]

(07-21-2015 12:36 PM)cruff Wrote:  

(07-21-2015 08:25 AM)Martin Hepperle Wrote:  are you aware of the PRM-85 project?

I acquired a PRM-85 a while back, it works great. I reprogrammed the EPROM on mine from the original 85A version to work with the 85B I later acquired. If anyone is going to make a similar board, you might consider placing a switch that would be easily accessible when the board is mounted in a module case, such that the service ROM could be quickly enabled and disabled without having to open the case.

I used a different approach I use six 8K EPROMs instead of one big ROM, four of which are selectable from any one of the 15 common ROM images for 86/87 (the ROMs for 83/85 are a subset) and the remaining two ROMs are fully configurable for any one of the 255 select codes available in case one wanted to create their own ROM. I use a different approach for the Diagnostic ROM too, I have an original diagnostic ROM that is the only occupant of a 82936A and on the odd occasion that I want to run diagnostics I just plug in the card.

I also designed one for 85A that has the 85B mass storage, Edisk, and Extended mass storage along with the I/O ROM in a 32K EPROM and then four more fully selectable 8K EPROMs.