Superdos in upper memory

[vdc300]

I used to own a switchable DOS cart with Dragon DOS and SuperDOS E6 on, it had a switch on to select the version, the superdos would load up into upper memory giving you all of the standard D32 memory to play with. Does anyone know how that was achieved and if any emulators support it. XROAR etc.

Thanks

[sixxie]

Not sure what you mean. DOS is always in the upper part of address space,
was this just a switch on the chip selects?

[prime]

Not sure what you mean. DOS is always in the upper part of address space,
was this just a switch on the chip selects?

Maybe he means that it was patched to have it's buffers in the $E000-$FEFF area, I guess that could work if you have a 64K machine and on cold start copied $8000-$FEFF to RAM. Humm I do have the partly commented disassembled source for Superdos, I wonder......

Phill.

[vdc300]

Hi

Yes to both

Now I come to think of it, it must of been on the 64, and I suppose it was the buffers, the main advantage I remember was that the Text and Graphics screens memory stayed in the same place rather than moving up 1024 or was in 4096 bytes?

I still have the 64 but not the Dual-DOS cart, I do have a DOS cart with DOS 4.0 on, and a spare 128 or 256 ROM that I was considering putting both DOS 4 and SuperDOS on and switching the address lines over. I think I remember reading another POST on this website on how to do that (it may have been on the old forums)

Thanks