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

I just tried a slightly different approach to selection of a DOS. I 
removed the "disk11.rom" entry from the MESS/BIOS/coco3h directory and 
put DOS10.ROM, DOS11.ROM, RGBDOS.ROM in the SOFTWARE directory.

After starting MESS coco3h in Extended Basic, I then mounted any of the 
above three DOS roms. None auto-started but all started correctly after 
an EXEC&HC002. All disk operations were correct for any of the roms so 
mounted.

The only problems with the above are that these carts must be mounted 
from within emulation. Emulation will crash if these ROMs are mounted in 
the Windows gui as Carts. Also Hard Reset within emulation drops back to 
Extended Basic and the cart is no longer mounted. This last action looks 
like a MESS bug as that does not simulate a real Coco where the cart 
might not autostart but it certainly would not pop out of the cart slot. :)