RAM at $600 or $3000?

[Ecernosoft]

Hello!

 

I was wondering if it's possible to have RAM at $600 or $3000... I understand $3000 is the HSC and I plan to have HSC support, so this is more of a question for $600.

This is also mostly for the E200, as if it's going to work I'm going to need RAM for it. Now, before you say "But you can't put stuff there", according to the 7800 Software Guide you can!

In fact, you can also put ROM/RAM at many other places too! Here's the memory map for 7800:

; Apparently there is a BIOS conflict at $2800-$2FFF... is the BIOS accessable in normal operation? If it is, we can ENSURE the player is actually using a REAL cartridge. First, the POKEY (Or in this case, E200, as I plan for it to have a COPYRIGHT register which always holds a specific value, in this case, $E2) random number test, then the ROM is actually RAM test (Write to anywhere from $3000-$FFFF and see if it actually succeded),  and finally the BIOS test (Check for the BIOS at $2800-$2FFF).

 

 

So, we thought the max ROM was 52K... Well, really it is actually 58K. You really only need 56K ($600-$17FF, and $3000-$3FFF) and in this case, I think I'm going to make a special mapper chip for ICT3 (The E300) with 5K of RAM at $600-$17FF (for the E200, unfortunately this limits you to 80 samples) and 48K of ROM ($4000-$FFFF) with a banked area at $4000-$7FFF or $8000-$CFFF (So that ICT4 gfx data can be used). This would allow for 96 KB of ROM as all 48K of ICT 3 could be used, as well as all 48K of another game.

 

Just an idea.

 

None of this will absolutley happen, as I think I'm just going to go with the standard POKEY and worry about amazing sound for ICT4.