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ricard · 15th Oct 2011, 10:22 pm

Ok, so this is sligthly off-topic as it is not related to a vintage computer as such, but it is related to mid-80's microcontroller technology, so I'm giving it a shot:

I'm trying to disassemble a ROM for a system (a Roland D-50 synthesiser if you must) that contains a NEC µPD78312 microcontroller. Initially, I thought it was the same opcodes as for the µPD7812, for whom I found both a disassembler and complete data sheet on the 'net. But after disassembling the code it appears the opcodes (and possibly the instruction set too; I haven't checked in detail) are different. Although there are several links to µPD78312 datasheets on the 'net too, none of them actually list the actual opcodes used (although in some there are tables of what the various machine language instructions do, cycle timings etc, but no actual opcode maps). And I haven't found a disassmbler either.

So I'm wondering if anyone here would have some documentation for the 78312 which they could share, such as scanning a page with the opcode map from a processor user manual, or something similar. [Source code for] a disassembler would be even nicer, but probably even more rare.

15th Oct 2011, 10:22 pm	#1
ricard Octode Join Date: Mar 2006 Location: Lund, Sweden Posts: 1,632	NEC µPD78312 opcode map anyone? Ok, so this is sligthly off-topic as it is not related to a vintage computer as such, but it is related to mid-80's microcontroller technology, so I'm giving it a shot: I'm trying to disassemble a ROM for a system (a Roland D-50 synthesiser if you must) that contains a NEC µPD78312 microcontroller. Initially, I thought it was the same opcodes as for the µPD7812, for whom I found both a disassembler and complete data sheet on the 'net. But after disassembling the code it appears the opcodes (and possibly the instruction set too; I haven't checked in detail) are different. Although there are several links to µPD78312 datasheets on the 'net too, none of them actually list the actual opcodes used (although in some there are tables of what the various machine language instructions do, cycle timings etc, but no actual opcode maps). And I haven't found a disassmbler either. So I'm wondering if anyone here would have some documentation for the 78312 which they could share, such as scanning a page with the opcode map from a processor user manual, or something similar. [Source code for] a disassembler would be even nicer, but probably even more rare.