Search found 760 matches

by Nemesis
Fri May 03, 2019 5:16 am
Forum: Mega/SegaCD
Topic: Questions on writing a new Mega CD emulator
Replies: 114
Views: 9320

Re: Questions on writing a new Mega CD emulator

While MegaCD emulation is still very much on my to-do list, I have compiled a fair few resources for it over the years. There's one largely untapped resource you should take a look at. I own a couple of these Cross Product MegaCD dev units: https://segaretro.org/SNASM_Mega-CD . This has as part of i...
by Nemesis
Fri Apr 26, 2019 5:43 am
Forum: Exodus
Topic: Load roms externally?
Replies: 6
Views: 963

Re: Load roms externally?

One thing that makes it slightly more complex is how ROM loading works. Exodus can't actually load a ROM. A ROM is just a blob of arbitrary data. Out of context, it means nothing. Exodus doesn't have anything about a Mega Drive hard-coded at all, as the system itself is just defined by a bunch of po...
by Nemesis
Tue Apr 16, 2019 1:39 am
Forum: Exodus
Topic: Load roms externally?
Replies: 6
Views: 963

Re: Load roms externally?

Not currently I'm afraid, right now there are no command line arguments. Support for them could of course be added, but I'd have to give some thought as to what I'd support on the command line, and how it would be implemented.
by Nemesis
Mon Apr 08, 2019 11:36 pm
Forum: Exodus
Topic: Active Disassembly - Post Processor
Replies: 14
Views: 1122

Re: Active Disassembly - Post Processor

I've had a solid play around with Ghidra, and written an experimental active disassembly script export function for it. There are a few dealbreakers with using it for ROM disassembly currently though: 1. There appears to be no way to cleanly export its disassembly in a compilable form. The tool was ...
by Nemesis
Mon Apr 08, 2019 2:18 am
Forum: Exodus
Topic: Crashing with Watchpoint Set
Replies: 3
Views: 465

Re: Crashing with Watchpoint Set

Here please. I'm using a Jira instance for issue tracking, which theoretically would be the more correct location to report issues in the future, but I'm not monitoring it for other people adding content, so if you report something there I'll never see it. As for the repo, I want to keep that clean ...
by Nemesis
Sun Apr 07, 2019 12:47 am
Forum: Exodus
Topic: Crashing with Watchpoint Set
Replies: 3
Views: 465

Re: Crashing with Watchpoint Set

Thanks, that was very helpful. I've found the issue, there was a missing lock that caused a race condition. I've pushed a fix under EX-346. Since this is a pretty major issue that affects debugging in general, I'll probably push out a new build in the next few weeks.
by Nemesis
Sat Apr 06, 2019 4:16 pm
Forum: Exodus
Topic: Active Disassembly - Post Processor
Replies: 14
Views: 1122

Re: Active Disassembly - Post Processor

You don't have to complain about IDA anymore, Ghidra is free, supports the 68k/z80, has a decompiler (that works for said processors) and has been used by NSA for years. Oh snap! I hadn't heard about this, just had a 5 minute play around. Damn, that is a nice tool, and the decompiler they've got wo...
by Nemesis
Wed Apr 03, 2019 10:54 am
Forum: MegaLD
Topic: MegaLD Dumping Project
Replies: 73
Views: 39700

Re: MegaLD Dumping Project

Here's a picture from the dungeon showing a digital data rip in progress: http://nemesis.exodusemulator.com/MegaLD/MegaLDRip.jpg It takes about 24 hours to rip each side using this technique, as the Mega Drive isn't capable of pushing the sector data out as fast as it comes down from the disk, so I ...
by Nemesis
Wed Apr 03, 2019 1:42 am
Forum: MegaLD
Topic: MegaLD Dumping Project
Replies: 73
Views: 39700

Re: MegaLD Dumping Project

I haven't bothered to compare the format and breadth of codes between the various standards, but there are features that are unique to Laserdiscs. Picture stop codes are an example, which cause the player to automatically pause when they decode a frame with a stop code. It's worth noting however, th...
by Nemesis
Wed Apr 03, 2019 1:23 am
Forum: Exodus
Topic: Active Disassembly - Post Processor
Replies: 14
Views: 1122

Re: Active Disassembly - Post Processor

The assembly output is meant to be generic, however I'm not sure there's such a thing as "standardised" 68000 assembly. I do all my testing and compilation with asm68k.exe, which is an oldschool assembler from long ago. IDA ( https://www.hex-rays.com/products/ida ) is an absolutely incredible disass...
by Nemesis
Wed Apr 03, 2019 1:08 am
Forum: Exodus
Topic: Exodus 2.1 release soon (Now available!)
Replies: 40
Views: 7091

Re: Exodus 2.1 release soon (Now available!)

Memory could be a problem. 6GB of RAM isn't a lot nowadays (IE, Google Chrome is using 2GB by itself right now on my laptop). Exodus uses large lookup tables to accelerate performance in some areas, and you should expect it to use up to 1GB of RAM in normal operation. Active disassembly however effe...
by Nemesis
Wed Apr 03, 2019 12:58 am
Forum: Exodus
Topic: Active Disassembly
Replies: 13
Views: 2949

Re: Active Disassembly

That probably won't yield very much, as the active disassembly feature can already scan down known code execution pathways even if they aren't actually seen being taken while the game is running. Most opcodes have known potential resulting addresses, including your basic conditional branch instructi...
by Nemesis
Wed Apr 03, 2019 12:37 am
Forum: MegaLD
Topic: MegaLD Dumping Project
Replies: 73
Views: 39700

Re: MegaLD Dumping Project

Oh, on re-reading, if you just meant capturing the codes in the vblank region as some kind of data stream rather than image data, well that's technically possible now. Even though decoding the NTSC video from the RF signal is problematic still, the control codes are perfectly contained in the compos...
by Nemesis
Wed Apr 03, 2019 12:14 am
Forum: MegaLD
Topic: MegaLD Dumping Project
Replies: 73
Views: 39700

Re: MegaLD Dumping Project

I did think about that, but in itself that was challenging, as I'd need to construct a delay line to offset the vertical sync position, without throwing the horizontal sync out of alignment. I never attempted to build one, but I actively looked at how I might construct this kind of setup. It's clear...
by Nemesis
Tue Apr 02, 2019 5:58 am
Forum: MegaLD
Topic: MegaLD Dumping Project
Replies: 73
Views: 39700

Re: MegaLD Dumping Project

If anyone's interested in reading a bit about the evolution of the software video decoding efforts, the best record is captured here: https://forum.lddb.com/viewtopic.php?f=32&t=2671 This doesn't contain some of the more recent discussions and results, but it has a lot of the steps leading up to whe...