MCL68+ A Motorola 68000 drop-in emulator

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MicroCoreLabs

New Tinkerer
Oct 8, 2023
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I would like to share my latest project, a Motorola 68000 drop-in emulator called the MCL68+. The CPU emulation is written in C and runs on a Teensy 4.1 micro controller board. I made a small PCB which contains a number of buffers and registers to break out and de-multiplex the Teensy's limited pins to the 68000's 64 pins.

I thought now would be a good time to share my progress in case I never get any further along! 🙂

 
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MicroCoreLabs said:
I would like to share my latest project, a Motorola 68000 drop-in emulator called the MCL68+. The CPU emulation is written in C and runs on a Teensy 4.1 micro controller board. I made a small PCB which contains a number of buffers and registers to break out and de-multiplex the Teensy's limited pins to the 68000's 64 pins.

I thought now would be a good time to share my progress in case I never get any further along! 🙂

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I wonder if it's possible to optimize that enough to make the 68000 emulation into 68010 emulation or have it emulate an 020 or 030 (probably at 16MHz or lower)
 
I dont see why not. Well, the CPU emulation would definitely be possible, but I think the Teensy is maxed out at 8 MHz for the local bus! :) Could port it to a faster microcontroller though - the foundation is all there.
 
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Thank you for the kind words! :) I guess a project like this is just the culmination of skills gained from sporadic successes throughout decades of frequent failures.
 
i love fun projects like this where there's not much practical use, but it works. a lot of people generally dismiss the fun stuff... ugh!
very nice work, would love to see it open sourced if possible.
 
"i love fun projects like this where there's not much practical use,
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Art for art's sake. Thanks!

MCL68, the 68000 emulator code, is already is open-source. I'll post this project when it's a little further along.
 
Update on this project: I fixed the remaining issues with the 68000 opcodes using Tom Harte's test suite and got some pleasant results!

The latest code is uploaded to GitHub: MCL68+GitHub

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Really awesome. Just awesome.
Can you make it emulate additional ram as well? Really what I want is an emulation of some awesome 68040 upgrade or something so that it can make an SE into a better-than-se/30 machine. :p

regardless, this is so cool. Software-defined processor.
 
MacOfAllTrades said:
Really awesome. Just awesome.
Can you make it emulate additional ram as well? Really what I want is an emulation of some awesome 68040 upgrade or something so that it can make an SE into a better-than-se/30 machine. :p

regardless, this is so cool. Software-defined processor.
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Maybe could emulate a little more RAM but not much. The Teensy 4.1 only has 1 MB of available RAM in total. Maybe 640KB is possible :)
 
MicroCoreLabs said:
Maybe could emulate a little more RAM but not much. The Teensy 4.1 only has 1 MB of available RAM in total. Maybe 640KB is possible :)
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I second this idea. The SE would benefit from having extra ram. Would it be hard to integrate a different Teensy with more memory available? Where do i send coffee donations? :D
 
ve7xpo said:
I second this idea. The SE would benefit from having extra ram. Would it be hard to integrate a different Teensy with more memory available? Where do i send coffee donations? :D
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If he teensy can be attached to an sd card it could use that sd card as ram (basically long winded virtual memory ). I have no idea if this would be so much slower that it’s worthless or if speeds of the critical path (processor to teensy to as card and back) are so much faster that it’s worth it.
 
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