PCbox, an add to the MS-DOS 1.25 project

Hallo allemaal,


Going through my "still to do" projects I ran into the Sofbox: 
http://mikenaberezny.com/hardware/pet-cbm/sse-softbox-z80-computer/

This is a CP/m 2.2 computer that loads its programs from (at least?) 
a 8050 and uses the CBM as terminal. The communication between these 
two goes over the IEEE bus as well.

This triggered the idea to see if it is possible to create a DOS 
equivalent. The hardware shouldn't be a problem: any PC with a 
bi-directional LPT port and a COM port should do. The needed extra 
hardware is described on http://www.baltissen.org/newhtm/cbmhd.htm  

How is this going to add to the MS-DOS 1.25 project? As said before, 
I'm convinced that the only thing that is needed to do to make any 
MS-DOS work on the CBM-II with a 8088 card is changing IO.SYS. If 
that is true, it should work for the PCbox as well. 

What about the software? The softbox comes with its own terminal 
software. Thanks to Mike Naberzeny and Doug Staley it has been 
disassembled and the sources are available. I first thought about to 
use it as-is but then I remembered Michał's remark about the back 
slash. 

I don't know what all is needed to develop the software for the 
MS-DOS 1.25 project but if it takes 15 minutes to create a disk 
image to test something, it will be long evenings.
In case of the PCbox I can develop things on a PC and write only the 
changed parts to a boot floppy. Yes, a boot floppy. The greatest 
advantage of PCbox is that it can boot form its own floppy. So we 
can start testing things with providing a new INT 10h for the video 
and new INT 16h for the keyboard. Once this works, we can work on 
INT 13h. We can change it in such a way that drive A points to a PC 
drive and drive B points to an IEEE drive.

Do I have to start here from scratch as well? No. I have PC-DOS (or 
MS-DOS ?) 1.1 including it sources. Including that of IO.SYS / 
IBMIO.SYS. 

After having prooven that IO.SYS is the only file needed to be 
changed, it is a matter of writing one for the CBM-II. But I warn 
you, it will be a completely different one. 


--
   
Kind regards / Met vriendelijke groet, Ruud Baltissen
www.Baltissen.org







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