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Do you mean from $40 to $FF right?

Well, for 3 reasons: 1: Because i'm not sure if i can play NTSC games on my PAL console, but in case i can, i'll play slower (at 50hz) and with black borders at top and bottom of the screen (because increased screen resolution in PAL). 2: Because the Atari 7800 was designed to be NTSC 3: Because if PAL games don't work on NTSC systems, maybe i can play the PAL versions i have but with correct resolution/speed Debugger

Erm... guys what reply speed is this? Mm nice to see the modification is suited for ntsc systems too, those are good news (and bad too because i'll have to buy two consoles, then) By some reason or other i tought the upload worked in another way, maybe because the ones i use at work (not for atari, of course) work in a completely different way. The reason to wanting to convert a PAL 7800 into NTSC is that i have more than one PAL consoles, but 0 NTSC ones Thanks for the ultra fast responses..

Hi all I'm just curious about a text file i readed somewhere, about converting a PAL Atari 7800 into a homebrew dev system. Considering that (afaik) the bigger base of Atari 7800 users have a NTSC system, why is this modification suited only for PAL consoles? And why anyone would like to put an EPROM instead of the original console BIOS? And the last question.... I don't have any NTSC 7800, mine is PAL, but i love NTSC I would like to convert one of my consoles to NTSC but i haven't found any information about this, maybe it's not possible? Sorry for not pasting the URL, but i can't remember where i dowloaded the file Debugger

Ok, thanks for all the responses, i think i know now all what i need to continue The only thing i don't fully understand is this stack/tia registers overlap, because it's fun to write to the registers pushing values, but this means that when i need to push something into the stack the console will become crazy, right? Eckhard: The secret project is a secret thing I don't like vaporware at all, so i preffer to work on this before i tell anything to anyone because for now it does not work at all and i don't even know if i'll be able to do it Btw, i have another question, but as it's a totally different thing i'll make another thread for it Debugger

Nice to meet you guys, and thanks for your responses Now i understand (more or less) how it's possible to boot for a game, so i can continue with my work; DanBoris thanks, i'm very very very interested in getting some more info about this register, i'll be very grateful if you can find anything EricBall, Happy_Dude, thanks to you too, now i'm a bit less confused... Booting from TIA/MARIA registers seemed a bit weird to me BTW: Anyone knows if any 2600/7800 game made use of any of the undocumented 6502 opcodes? Um... "SP is hardwired to page 1 ($0100-$01FF)" ? There aren't (again) TIA/MARIA registers in this address?

After spending ages searching google, i'm still unable to find some information i need to do a project. In particular, i need to know small things about Atari 7800 (and 2600) like what values are into PC and SP when the console is powered up, as i think it's not possible to have a 0 value because in address 0 there are the TIA/Maria registers... Can anyone help, please? Another thing that confuses me is the address where bios rom and the cartridge are located... Bios ROM seems to be overlapping some of the cartridge space, so this means there's something like a page swapping feature in any place, but where and how it works? Third and last one What format do have the cartridges? I mean, how data is stored? The console executes the cartridge game from the first byte or there are initial bytes with some obscure meaning? A big thankyou in advance guys Debugger