16 Apr
2005
16 Apr
'05
7:14 p.m.
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>
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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