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single stepping 68000 processor with cycle accurate display [message #10690] Tue, 09 April 2024 06:30
denis2342 is currently offline  denis2342
Messages: 23
Registered: February 2017
Junior Member
Hi

I have made three installations of a MC68000/MC68010 and MC68012 on an Arduino Mega to single step them with the first 4KB of RAM simulated by the Atmel MC.

The Microcontroller keeps the MC68k CPU waiting for DTACK so you can put anything in you want and see the cycles it needed for the mnemonic (take care of the prefetch).

My suggestions what you can do with it:

1. see that the MC68000 reads before it clears a memory location with CLR
2. test the DBcc loop of the 68010
3. see how the BUS ERROR stack frames is different between MC68000 and later processors
4. test the RMC on MC68012 which has a pin to show the RMC state
5. test the higher address bits on the MC68012
6. find errors in the Motorola documentation where the cycles for the mnemonics are not correct.
7. try to do stuff with the FPU on the MC68012 port.
8. request an interrupt and see what happens

telnet 79.210.189.35 68xx

Port 6800 for the MC68000
Port 6810 for the MC68010
Port 6812 for the MC68012 and a MC68881 FPU

For now I don't have an assembler on it and you need to put all commands in in HEX, sorry.

Denis

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[Updated on: Tue, 09 April 2024 06:36]

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