Search found 791 matches

by Nemesis
Tue Feb 20, 2024 11:25 pm
Forum: Exodus
Topic: Timing analysis using Exodus
Replies: 8
Views: 4136

Re: Timing analysis using Exodus

Nothing else from memory, just be aware the third party libraries haven't been updated, so they point at ancient versions that aren't all available on their original links anymore. If you use the wayback engine at archive.org you can pull down any missing ones. I'll be updating them soon.
by Nemesis
Fri Feb 16, 2024 12:08 am
Forum: Exodus
Topic: Timing analysis using Exodus
Replies: 8
Views: 4136

Re: Timing analysis using Exodus

Hey Matt, just letting you know I've pushed a change to Exodus which adds timing information for trace logs, both in terms of processor clock cycles and absolute system time since the last "hard reset": https://nemesis.exodusemulator.com/Exodus/Images/TraceLogTiming.png This is logged to file as wel...
by Nemesis
Tue Feb 13, 2024 9:54 am
Forum: Exodus
Topic: Timing analysis using Exodus
Replies: 8
Views: 4136

Re: Timing analysis using Exodus

I see what you're saying. I think adding timing information to the trace logs would be the right way to go. Using GetCurrentTimesliceProgress() is good, but you'd probably be more interested in a time in clock cycles. Logging both would be best most likely. All this could be done within the Processo...
by Nemesis
Mon Feb 12, 2024 11:42 pm
Forum: Announcement
Topic: Nuked MD - decap-based cycle-accurate Mega Drive emulator (software & FPGA)
Replies: 8
Views: 56742

Re: Nuked MD - decap-based cycle-accurate Mega Drive emulator (software & FPGA)

Really impressive work, good job guys! A transistor-level simulation of these devices is a great step for preservation.
by Nemesis
Sun Feb 11, 2024 10:39 pm
Forum: Megadrive/Genesis
Topic: I'm officially building a microcode-level 68000 core
Replies: 52
Views: 112941

Re: I'm officially building a microcode-level 68000 core

Posting here to keep the updates flowing. Things have moved slower since my leave ended and I've started back at work, but it's still moving along. I've been able to fully decode the microcode in the production version of the 68000, and generate a listing for it in the same form as Appendix H in the...
by Nemesis
Fri Feb 09, 2024 6:25 am
Forum: Demos
Topic: Instruction timing test (68000)
Replies: 8
Views: 8481

Re: Instruction timing test (68000)

Huge thanks for this test ROM! I've started work on Exodus again, and I'm currently working on a microcode-level 68000 core that should get this to 100%. I was about to write a test ROM like this myself when I came across yours. These kind of tests are invaluable, thanks for putting it together!
by Nemesis
Sat Feb 03, 2024 2:15 am
Forum: Megadrive/Genesis
Topic: I'm officially building a microcode-level 68000 core
Replies: 52
Views: 112941

Re: I'm officially building a microcode-level 68000 core

A quick note to say I've updated my 68000 annotated schematic here: https://github.com/RogerSanders/M68000Schematic I've corrected a lot of register names, and identified more latches and regions in the die. You can view the annotated schematic using the Schematic Explorer tool I put together an age...
by Nemesis
Sat Feb 03, 2024 1:21 am
Forum: Megadrive/Genesis
Topic: I'm officially building a microcode-level 68000 core
Replies: 52
Views: 112941

Re: I'm officially building a microcode-level 68000 core

Math operations, flags, and the ALU You should know there's another patent which covers the 68000 ALU specifically, and in some cases goes into more detail than US4325121. That patent is US4312034 here: https://nemesis.exodusemulator.com/M68000/Patents/US4312034.pdf Before we talk about the ALU, it...
by Nemesis
Thu Feb 01, 2024 8:30 am
Forum: Megadrive/Genesis
Topic: I'm officially building a microcode-level 68000 core
Replies: 52
Views: 112941

Re: I'm officially building a microcode-level 68000 core

The Execution Unit So far we've covered how to determine the sequence of microinstructions that are executed for a given macroinstruction (opcode). Now we'll dive into what those individual microinstructions can do. The most critical component for this is the Execution Unit. There's an entire separ...
by Nemesis
Tue Jan 30, 2024 10:59 am
Forum: Megadrive/Genesis
Topic: I'm officially building a microcode-level 68000 core
Replies: 52
Views: 112941

Re: I'm officially building a microcode-level 68000 core

Prefetch and initial state Before you can properly understand the steps an instruction takes during execution, it's important to understand the state the processor is in before the instruction starts executing. Before each "normal" instruction (non-exception) begins executing, the following state i...
by Nemesis
Mon Jan 29, 2024 11:17 am
Forum: Megadrive/Genesis
Topic: I'm officially building a microcode-level 68000 core
Replies: 52
Views: 112941

Re: I'm officially building a microcode-level 68000 core

Mega bump to say that 5 years later, I've picked up Exodus again and I'm currently looking at this very issue once more. In the next few days I'll be writing up a post describing the opcode decoding steps taken by the processor, and a little "microcode 101" description that explains how to interpret...
by Nemesis
Thu Jan 25, 2024 11:20 pm
Forum: Exodus
Topic: Trying to compile Exodus
Replies: 8
Views: 14534

Re: Trying to compile Exodus

Sure, I'd be happy to accept the contribution! Best thing to do might be to fork the repo and put your changes on your fork. I'm happy to do any tidy-up and do the merge myself, or if you feel it's in a good enough state, feel free to do a pull request and I can check it out in that. Just be aware -...
by Nemesis
Tue Jan 23, 2024 10:01 pm
Forum: Exodus
Topic: Return to active development - Now MIT licensed!
Replies: 2
Views: 319

Re: Return to active development - Now MIT licensed!

I should add, there were some critical race conditions that caused crashes or lockups on the latest available release on my new PC. I have fixes for those issues in the repo now, so if you've had trouble running Exodus in recent years, a fix is incoming. I've had it running stable for the last 24 ho...
by Nemesis
Tue Jan 23, 2024 9:58 pm
Forum: Exodus
Topic: Trying to compile Exodus
Replies: 8
Views: 14534

Re: Trying to compile Exodus

I'm going to make this much simpler going forward, so that it's just a "pull and build" experience. Not there yet though.
by Nemesis
Tue Jan 23, 2024 9:57 pm
Forum: Exodus
Topic: Annotated disassembly For Exodus?
Replies: 1
Views: 88835

Re: Annotated disassembly For Exodus?

The "Active Disassembly" feature will do what you're after. It uses fairly complex runtime analysis of the code as it executes to generate rich disassemblies that can be recompiled.