[Coco] Dos ROMS.

[Robert Gault]

Phill Harvey-Smith wrote:
> Hi,
> 
> I'm just implementing multiple DOS rom support in Mess, I have it 
> working correctly for the Dragon, so that now you can select which of 
> the following dos roms you want to use : DragonDos 1.0, SuperDos E6, 
> Cumana Dos, Eurohard DragonDos 4.0 or DosPlus, you can also elect to 
> have no dos rom loaded, so that the machine may be booted as cassette only.
> 
> I would like to implement the same for the CoCo, and have a couple of 
> questions.
> 
> 1) I know there was a 1.0 version of RS-DOS, and that Mess uses RS-DOS 
> 1.1, is the 1.0 rom available anywhere ?

It has been my understanding that MESS will use for the coco2 and up 
emulation anything with the name disk11.rom. That is not pretty and it 
means renaming files whenever you want to switch to a different version 
of DOS, but it works.

The 1.0 ROM is available (probably on the Coco3 site) and I can supply a 
copy if needed.

> 
> 2) Where there other doses, available also that where compatible with 
> the standard RS-DOS cart ?

Several were available usually as patches to DOS1.0 or 1.1. They worked 
best when loaded over the Tandy DOS, copied to lower RAM, and then 
burned to an EPROM.

ADOS and ADOS3 has been discussed here lately. I use my own version of 
RGBDOS (used with the Ken-Ton hard drive system) and Cloud-9 has their 
version called HDBDOS. There were others.

> 
> 3) The mess driver for the CoCo3 seems to load the RS-DOS rom twice, 
> once at the normal $C000 and also at $E000, is there any special reason 
> for this, or is it just down to the address decoding in the RS-DOS cart ?
> 
> Cheers.
> 
> Phill.
>