HP82143 Processor details

[blackjetrock]

After a bit of investigation and coding I think I have a dumpo of the ROM.

Along the way I found that my port of Sean's code didn't work too well on my Pico. i examined the datasheets and found that firstly, the 3870 seems to be a dynamic device so you have to keep the clocks running for it to operate. At a minimum of about 1MHz. After that difficulty I wrote my own dumper which can insert arbitrary code into the device (as opposed to Sean's dumper that inserts a couple of instructions). I needed this as I didn't and still don't get consistent values from memory addresses. i suspect it's some timing issue. Instead of fixing it I read each location a few hundred times and only if they are the same do I use that value.
the instructions that are injected are in a table, so you can run whatever you like on the device.

After collecting the values that the code decides is the correct one for each memory location you get a dump of the ROM.
I have dumped the Boris again and get a very similar dump this time. I dump 4K each time and get a difference when off the end of Sean's dump. Not sure why.

I have also dumped the printer ROM.

Andrew