RhinoPower Ltd

The memory size is 4k on the 84-pin chips so it sits at C000h in the memory map, you may have more or less memory. To read the memory you need to load a program into an external memory device that will then be run in Mode 0 and will read the internal memory out through the serial port so you need to find that as well, you may have some test points on those traces. I use a 27C256 as the external memory and place the ROM reader programme lower down on the memory map to avoid bus contentions with internal memory.

I tend to just dump the entire memory map, it will copy the RAM and the reader programme but that can be edited out. The code usually starts at the bottom of the memory so that's easy to find. The Stack Pointer is set to the end of RAM, that location will be found in the first few bytes of RAM. You only have a 16-bit address bus so the memory range is 64k max.

Do you have access to an ECU with an external EPROM? if not then you won't easily be able to determine the pins for the data and address lines, it is possible but its extra work.

I originally had a Suzuki Vitara with a 70E10 ECU, this had an 84-pin chip with an external EPROM; that was the first of these processors that I reversed engineered. The mode pins will be near the crystal somewhere, I did have an ECU with the 100-pin chip years ago but I've no idea what happened to it. I'll have a look for it - it may just have been an odd one that came in for repair.

Edit: I found the ECU very quickly, its an MD759132 which Google says is a Mitsubishi FTO Gearbox ECU, the one I have has no EPROM fitted, I'll have a look for that too.

-- Edited by TechSupport on Sunday 15th of March 2020 12:02:01 PM