cctech Digest, Vol 20, Issue 31

[Jim Attfield]

If you hit T from an RDOS prompt it will enable the upper 32K, copy itself
to 0xC000 and re-issue the prompt. I'm not quite sure where the stack goes,
perhaps K still works to kick the stack. Not sure if this also works on a
4FDC

Jim

 Message: 12
> Date: Sat, 16 Apr 2005 00:04:20 -0500
> From: "Randy McLaughlin" <cctalk at randy482.com>
> Subject: Re: Some said they have CDOS and Cromemco disks
> To: "General Discussion: On-Topic and Off-Topic Posts"
> 	<cctalk at classiccmp.org>
> Message-ID: <003b01c54241$c76faf60$023dd7d1 at randylaptop>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> 	reply-type=original
> That's great!  I can make a few suggestions:
>
> I can send you older CDOS's that should be more memory lean.  Some older
> CDOS's had normal SA800 support via undocumented drive type 'X'
> even though
> CDOSGEN only references 'S'mall & 'L'arge.
>
> If you have 64K of RAM RDOS can be copied to RAM giving you access to the
> full 64K allowing Larger CDOS's:  Using a random address such as 1000H:
>
> ld hl,0C000H
> ld de,2000H
> ld bc,1000H
> ldir
> ld a,1
> out (40H),a
> ld hl,2000H
> ld de,0C000H
> ld bc,1000H
> ldir
> ret
>
> Just use the substitute memory command to enter the above code
> (hex) and do
> a g 1000 (a return returns to RDOS).  You are now running RDOS out of RAM.
> You can have one 32K CDOS and maybe a 64K CDOS to transfer.  BTW you never
> have to use 8080 only opcodes since RDOS & CDOS only run on
> Z80's.  Also the
> above code can go in any free space and is not address dependent.
>
>
> Remind people of my favorite mantra:  3.5" drives with DD media will be
> happy to act as 5.25" DD drives.
>
>
> Randy