Some said they have CDOS and Cromemco disks

[Dave Dunfield]

Hi Randy,

>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.

That would be ideal - It would be nice if I could skip the intermediate
step of making a SSSD and go straight to making the final disks. It would
also eliminate the requirement to have 48k in order to transfer the final
disks.

I'll email you the transfer program - perhaps you can read in a version
of CDOS that INITs in 32k and send it back to me.

Btw, it's pretty easy to test:
- Gen a CDOS for 32k
- Boot it, run INIT but don't respond to the first prompt
- Reset system
- Enter G100
- INIT will startup again, try formatting DSDD disk and see if it works.

When I try to do a DSDD disk under 32k CDOS I get:
  Logical disk error 03h, drive 'h', block BC7241h

Under a 48k or 64k CDOS it works fine.


>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.

I thought about doing this - in fact, you can use the 'T' command to cause
RDOS to copyitself to RAM ... but I would like to keep it running in 32k
as this is more easily achieved configuration in many cases.


I've put together a bit of documentation, and I have the transfer program
as well as CDOS and Cromix images ready to put up, however I'm having a bit
of trouble with permissions on the server (which is remote to me)... I
hope I can get it resolved this weekend and get the files up.

Regards,
Dave
-- 
dave04a (at)    Dave Dunfield
dunfield (dot)  Firmware development services & tools: www.dunfield.com
com             Collector of vintage computing equipment:
                http://www.parse.com/~ddunfield/museum/index.html