+retroclouds Posted July 8, 2011 Share Posted July 8, 2011 I want my cartridge game to run on a V2.2 console. Now we know that with the V2.2 consoles ROM-only modules no longer work. Basically the TI selection screen doesn't scan ROM banks anymore. From the TI-INTERN book; 01FD : CEQ @>6000,>AA ROM Header? OH!!! / Not at GROM V2.2 0202 : BR GROM@>0224 / 0204 : DST @>8358,@>6006 Next program start / The other shifted 0209 : DCZ @>8358 / accordingly 020B : BS GROM@>0224 / 020D : INCT @>8372 / 020F : DST *>8372,>FFFF Flag on stack / This change eliminates 0214 : INCT @>8372 / the ROM moduls 0216 : DST *>8372,@>8358 Address on stack / 021A : INC @>836C 2nd program? / 021C : DST @>8358,@>0000(@>8358) / 0222 : BR GROM@>0209 / So I'm trying to find a way how to start my game on an (unexpanded) V2.2 TI-99/4A anyway. These are the options I'm thinking about 1) Bypass the TI-Title screen and start the game right away. There are couple of game modules out there that do that. I think the Milton-Bradley games do that. Is that possible without adding any extra hardware to the cartridge ? Does the DSR scan routine also check the cartridge space. Would that help? 2) Add a "CALL GAME" command to TI-Basic that branches to the game in the cartridge space. Don't think that's possible without GROM on the cartridge. If we have GROM, then the game is scanned anyway. EDIT: How do they do it with Munchman and TI-Invaders? These are ROM only games, and I suppose they work on v2.2 consoles. Probably some extra chip on the cartridge ? 3) Write a fake VDP header on cassette tape to fool the GPL interpreter and start the game. You basically have the cartridge and a cassette tape. You load from the cassette tape to trigger the cartridge. No, that's not an option Any ideas ? Quote Link to comment Share on other sites More sharing options...
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.