Re: PCbox, an add to the MS-DOS 1.25 project

Hello!

Ruud@Baltissen.org wrote:

> 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  

But if you have a PC, what do you need a CBM-II for? A PC should also
have a monitor and keyboard, right? Or would you use a PC just a
development platform?

> 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. 

It is true that you can run MS-DOS on the CBM-II by changing its IO.SYS,
but you will not be able to run any PC programs that use INT 10h or INT
16h, or write to framebuffer etc.

That's why I wanted do it the other way around - writing implementation
of INT 10h, INT 13h etc so that original IO.SYS _and_ other programs
could work.

> 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.

No, ad for now it involves writing a TSR implementing PC interrupts,
uploading it to the CBM-II via RECV.EXE and testing PC programs (also
uploaded this way).

> 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.

Here I got confused. Will the "8088 softbox" be just an 8088 board where
INT 10h and INT 16h need to be emulated? If so, how does it differ from
the existing 8088 board for the CBM-II?

Regards,
Michau.

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