Venus Express on 800-Cart?

[Heaven/TQA]

would that be possible?

 

the dificulty is that i need the RAM in the area $1000-$cfff so i can not pleace ROM there but would it be possible to have a cart $f000? or $0500ff?

 

never played around with carts that's why i am asking...

[Rybags]

Can't be done. Cartridges only have enough address lines to allow 16K of addresses.

 

Aside from that, bank selecting would be the only option. And even then, as a minimum you have to use $B000-BFFF for ROM. I imagine their might be some way to have RAM there, but don't know if a method exists.

 

Early bank select schemes used the address range $D500-D5FF, and output a signal on a line called CARTCTL (I think) which bank-select hardware can use to employ bank-switching on the cartridge.

 

I've heard of systems which allow a small ROM at $5000, but don't know if they existed on production 800s.

[classics]

Use a switchable cartridge so you can turn off the ROM and use all of ram after loading.

 

If you send me your program I can see if it will work on 1mbit flash cartridges.

 

Steve

[+warerat]

Can't be done.  Cartridges only have enough address lines to allow 16K of addresses.

 

Aside from that, bank selecting would be the only option.  And even then, as a minimum you have to use $B000-BFFF for ROM.  I imagine their might be some way to have RAM there, but don't know if a method exists.

 

Early bank select schemes used the address range $D500-D5FF, and output a signal on a line called CARTCTL (I think) which bank-select hardware can use to employ bank-switching on the cartridge.

 

I've heard of systems which allow a small ROM at $5000, but don't know if they existed on production 800s.

1000686[/snapback]

 

You can disable the ROM by dropping RD4 and RD5 on the cart slot. Grounding RD4 would show the ram from $8000-$9FFF and RD5 would be $A000-$BFFF. Some bank switched cartridges latch them through /CCTL so you can turn off the ROM.

 

The XL/XE has the self-test ROM from $5000-$57FF selectable via PB7.