CreatiVEmu Forum

I can't find the original post - but here's the ZIP with all ROMS swapped.

Logically, poor choice of word but hey, the ROM image is arranged as

8000
9000
A000
B000

4000
5000
6000
7000

I really don't understand why we continue to do this - as it's pretty much proven to be false in almost all cases.

From the CPU there is only one ISR, it doesn't magically move around memory while you play

That did it! They work now, had to swap around the first 2 8k banks as well which I would never have thought of, did something similar for the 18k roms. It was doing my head in.
Thanks!

Its a confusing setup, Fabrizio Caruso x-games work fine as 16k roms but fail when doubled to 32k, but if the 2 8k banks are swapped and then doubled it works, is this the way its meant to work or have I got my Rom1 and Rom2 lines swapped around?

OK - let's think this through.

Where in memory does the original 16K ROM sit?

Why does it need to be anywhere else?

Is the earth still flat?

I can sort of understand that going from one bank of 16k to 2 banks of 16k could cause some issues but why would a 6k game like planet defender need to have the first 4k swapped with the second 2k (with extra padding) to make it work as an 8k rom?

kevgal wrote: ↑

Fri Mar 24, 2023 11:11 am

or have I got my Rom1 and Rom2 lines swapped around?

Hi,

/ROM2 for A13 is correct (at least for the "swapped" ROMs)
but you wrote you use /ROM1 OR /ROM2 as /CS or /OE => correct should be /ROM1 AND /ROM2

Cheers, TOM:0)

kevgal wrote: ↑

Fri Mar 24, 2023 1:07 pm

I can sort of understand that going from one bank of 16k to 2 banks of 16k could cause some issues but why would a 6k game like planet defender need to have the first 4k swapped with the second 2k (with extra padding) to make it work as an 8k rom?

That's because in the original cartridge there was a 4k EPROM and a 2k EPROM and they were wired in a particular way, mapping data as you know.
Later revisions of the cartridge feature a 8k EPROM and data distribution/mapping is maintained consistent with the 4+2k version
Same happens with very late versions of Basic, on a 16k EPROM as opposed to 8k + 4k

MADrigal wrote: ↑

Fri Mar 24, 2023 4:45 pm

kevgal wrote: ↑

Fri Mar 24, 2023 1:07 pm

I can sort of understand that going from one bank of 16k to 2 banks of 16k could cause some issues but why would a 6k game like planet defender need to have the first 4k swapped with the second 2k (with extra padding) to make it work as an 8k rom?

That's because in the original cartridge there was a 4k EPROM and a 2k EPROM and they were wired in a particular way, mapping data as you know.
Later revisions of the cartridge feature a 8k EPROM and data distribution/mapping is maintained consistent with the 4+2k version
Same happens with very late versions of Basic, on a 16k EPROM as opposed to 8k + 4k

.... and 6k ROMS have the 2K portion at $A000 or $A800 - so easier to mirror, as you don't need to know which is which, but not actually necessary if you do. It's just a lazy way to pirate the ROM.

I'm not knocking it ... it works - but we have so much more knowledge and information available to us now, it's really time to move on.

@username@ wrote: ↑

Fri Mar 24, 2023 5:23 pm

MADrigal wrote: ↑

Fri Mar 24, 2023 4:45 pm

kevgal wrote: ↑

Fri Mar 24, 2023 1:07 pm

I can sort of understand that going from one bank of 16k to 2 banks of 16k could cause some issues but why would a 6k game like planet defender need to have the first 4k swapped with the second 2k (with extra padding) to make it work as an 8k rom?

That's because in the original cartridge there was a 4k EPROM and a 2k EPROM and they were wired in a particular way, mapping data as you know.
Later revisions of the cartridge feature a 8k EPROM and data distribution/mapping is maintained consistent with the 4+2k version
Same happens with very late versions of Basic, on a 16k EPROM as opposed to 8k + 4k

.... and 6k ROMS have the 2K portion at $A000 or $A800 - so easier to mirror, as you don't need to know which is which, but not actually necessary if you do. It's just a lazy way to pirate the ROM.

I'm not knocking it ... it works - but we have so much more knowledge and information available to us now, it's really time to move on.

All correct
But I have just explained why the 6k games have data mapped that way since 1981

Scouter3d wrote: ↑

Fri Mar 24, 2023 1:22 pm

kevgal wrote: ↑

Fri Mar 24, 2023 11:11 am

or have I got my Rom1 and Rom2 lines swapped around?

Hi,

/ROM2 for A13 is correct (at least for the "swapped" ROMs)
but you wrote you use /ROM1 OR /ROM2 as /CS or /OE => correct should be /ROM1 AND /ROM2

Cheers, TOM:0)

Yes my bad, poor choice of words, that should AND.