SpritesMind.Net

Hi guys, I've been working away at something for the last couple of weeks. I have a lot of documentation, tools, images, and other bits and bobs archived for all kinds of Sega systems. Like, a lot, over 15 years worth. I've been trawling through it lately, trying to organise things better, catalogue...

Unfortunately the data is never passed on when it's in that mode. I'm on my phone and can't look things up properly, but IIRC whichever asic gets the raw data stream from the laser also exposes the TOC data, and it never passes the data on when it's doing TOC decoding. Only way I could get at that d...

Just doing a quick post to say I haven't forgotten about this or abandoned it. My wife gave birth to our fourth child about two weeks ago, and leading up to that I needed to devote extra time to getting ready and helping my wife, as well as getting things squared away at work. I'll be turning my att...

I think this discussion lack clarifying objectives. Is it "cycle accuracy" what are you aiming for? Is it speed? Perhaps a mix of both? And then what is “cycle accuracy” really?, as its name says should be that at the end of every cycle the chip status is the same as emulator status, but I bet no e...

It's mostly covered by Sik, but I'll add a bit more detail on a few points. The H counter is simple enough, here are the notes on it from my Emulator: // The internal hcounter is 9-bit, and the external hcounter is 8-bit. The upper 8 bits // of the 9-bit internal hcounter are used to build the 8-bit...

For illustrative purposes, here's an annotated profile snapshot of Exodus while executing a Mega Drive ROM: http://nemesis.exodusemulator.com/Exodus/ExodusThreads.png I've annotated the threads that are used for particular tasks of interest in red. You can see the 68000+Z80 thread spends almost all ...

Sorry, I meant to come back to this much sooner. A lot of good stuff has already been discussed so far. My reply is going to be a bit long, so apologies in advance. What started out as a simple reply has morphed into a kind of full introduction to the problem for the uninitiated. If you've already w...

I don't have time to do this justice right now, but I'll get back to you on this soon. My problem here will be reducing my comments from book length. When I designed Exodus, I deliberately took different approaches on a lot of things, with the threading and execution models being no exception. I can...

It originated from a guy on http://www.atari-forum.com. I'm not sure he really maintains it anymore, but he's still active there. You can find him in this recent thread talking about it: http://www.atari-forum.com/viewtopic.php?t=36648

All that said, I see the Microcode analysis ( http://gendev.spritesmind.net/forum/viewtopic.php?f=2&t=3023 ) as the way forward. Reading the microinstructions tells you what you need to know regarding cycle timing. I hope to extract simple, verified data tables at the end of that process to make thi...

Kinda. If you want to be able to verify perfect cycle accuracy for all bus timings for all instructions, you're out of luck. I did work on making one that measured bus timings within an opcode for particular sets of instructions, but getting repeatable, stable results out of it while avoiding infini...

I managed to track down a pdf of that "Microarchitecture of VLSI Computers" book that ijor mentioned. It has a lot of VERY interesting material on the 68000, much of which I haven't seen anywhere else. This book is a trade journal of sorts, being a compilation of papers presented at the "NATO Advanc...

I was going to make my next big post on how microinstructions are addressed and encoded, but before that I decided it was important to start with a primer on understanding the CPU schematic diagrams. It's taken longer than I thought to write this part up, so I'm going to post it now and cover the 68...

Well I may as well start to share what I've been working on. For the past few weeks I've been banging my head against my computer trying to write a simulator for galibert's netlist. ... Great work! I'm interested where this ends up. It'd be fantastic to be able to have something like that working. ...

I've finally completed the microcode transcription from the 68000 patents. It was slow and boring and took forever, but it's done now thank goodness. My primary sources were EP0019392B1 and US4325121 . Hopefully some of you will find the result useful. Now that the data is in a clean digital form, i...