This page will contain my tutorial (from many, many years ago) that I wrote in the early days of the Sega 8-bit (Sega Master System and Sega Gamegear) emulator, Meka.
Download the PDF here (when I find it again!)
My method (back in the old days!)
I had a spreadsheet – written by a friend using Excel VLOOKUP tables – that would convert almost any of the Action Replay codes into actual addresses in memory.
Using the DZ80 tool, I would disassemble the game via the ROM dump, then work out where the Action Replay code was tweaking the memory. I would convert this into a proper byte patch in memory, which Meka could then use to alter the game’s memory whilst it was running.
90% of the time this would be an exact hit, but sometimes a little jiggery-pokery was required to get to the actual code area that was decreasing the lives/energy counter(s).
This was all done many years before Meka then implemented the numerous code debugging/hacking add-ons.
Saved Game patches for Meka
Browsing through some old hard drive backups of a much, much older website, I found these two patches for the saved game.
After reading my own .NFO files it seems that, back in 2000, I couldn’t get all the hacks working as patches inside MEKA that I thought I could, so instead I released some saved game hacks for MS DOS.
- Aztec Adventure – Carry 255 of each of your special items.
- Gauntlet – 255 x keys and 255 x magic potions.
Note: These byte patches were written in the days of Windows 95 or maybe Windows 98. Use a DOS emulator to run them.
Other releases for Meka
Some other files that I found on the same hard drive backup were:
a) The Pro Action Replay for the SMS manual – typed in by hand by yours truly. I’d bought it to send to the original Meka coder as part of my registration fee to get the full non-shareware version.
b) A list of all the SMS, GG, SG-1000 & SC-3000 patches for use with Meka. Note that these used to be included with the Meka distribution files, but not these days it seems. I’ll need to try and recover my old SMSPower forum login to see what happened to my patches.
c) A lot of IPS patches for various ROMs. If you had version X of a ROM, but didn’t have version Y, you could use an IPS patch to create a copy of version Y from your version X. There are three ZIP files within this single one. Two are for SMS ROMs, and the third is for Gamegear ROMs.
This harks back to the days of the GoodROMs set of tools and the hunting of multiple versions of the same ROM. Sometimes there were just two or three bytes difference, but that then counted as a variant of the original ROM. An IPS tool would apply the patch to your ROM file (always on a backup!) and then you would put the new ROM into your GoodTools and see if it filled a gap in your collection.
d) A infinite lives trained version of Championship Loderunner. I did this hack way back in January 2000. Using DZ80 to hunt down the code that needed to be tweaked and issuing an IPS patch to put it into your own ROM – or click this link. If you download the ROM from my website, you’ll also find all the level codes inside the .ZIP file.
You will need an IPS Tool to apply it. There’s one in the download in item c) but you’re better off finding a more recent one, such as Floating IPS.