I admit, I am pushing my personal envelope (punching above my weight, beyond my pay-grade etc. etc.) on the trailing edge of technology. So please be kind!
I would like to write new firmware for a NEC µPD7800-series microprocessor system, with the aim of expanding the RS-232 command-set to interface with that microprocessor.
According to what I have found, the source code should use NEC's µCOM-87 instruction set. As I understand it, µCOM-87 includes the entire instruction set from the Intel 8080 (as originally inscribed on papyrus), with embellishments.
NEC's literature at the time (1990 Single-Chip Microcontroller Data Book; NEC Document #50053) indicates that the µCOM-87 source code should be sent to the "RA87 Relocatable Assembler Package for the µPD7800 Series" which will generate the object code to be burned to the EPROM.
As described in the NEC literature, the RA87 package would appear to be quite sophisticated/streamlined/efficient, and the six (6) separate programs of RA97 can be combined in different ways to arrive at usable object code.
Does anybody have any information/suggestions about the NEC RA87, such as
Where I can find a version of RA87 that can be run on a 'modern' DOS/Windows/Linux OS?
Is there an emulator for the NEC RA87?
Is there some other work-around, such as a different assembler that will work equally well?
Also, if anybody can offer advice regarding disassembly of the original firmware, that would be a great place to start this project.