Re: Once again musing about "DOS 3.3 for ProDOS"

[Steve Nickolas <lyricalnanoha@usotsuki.hoshinet.org>]

On Thu, 15 Dec 2011, Oliver Schmidt wrote:

> Hi Steve,
>
> > This time I'm armed with a basic understanding of the ProDOS API, but
> > still don't understand the inner workings of DOS.
>
> You write "this time" and "once again" but even after some search I
> don't find the discussion you seem to refer to...

Every couple years I get the idea.  I remember bringing it up at least 
twice here, hence "once again".

> > The source of PDOS RDOS tells me what I need to know about interfacing on
> > a basic (lol) level to ProDOS but I haven't seen something similar for DOS
> > 3.3.  I am thinking I will want to merely patch out the file manager and
> > RWTS, and replace INIT with BYE.  Doing the former is the most difficult.
>
> I seem to be unclear of what you want to want to archive. For many
> BASIC programs the existing BASIC.SYSTEM is already a sufficient "DOS
> 3.3 emulation". And when it comes to RWTS access then the general
> question would be how to map those accesses to ProDOS. Not talking
> about implementation issues but about conceptual questions. If some
> program reads some sector on some track it most likely presumes a DOS
> 3.3 layout with a DOS 3.3 catalog / vtoc / etc. The only way I see
> such a program working in a successful / meaningful way on a higher
> capacity drive is to work with DOS 3.3 partitions or DOS 3.3 disk
> images.

BASIC, yes.  But I've dealt with a few DOS programs where they do things 
BASIC.SYSTEM doesn't like (a lot of chargens do that), or they access DOS 
through the print chr$(4) trick in machine code (almost anything 
compiled), - these programs could be made to work in this way, even if the 
RWTS is not DOSsy enough, even if the catalog is not DOSsy.

THIS is what I hope to achieve, and it doesn't need the "dos.master" 
approach of doing a block-mapping emulation of the drive over top of DOS 
3.3.

-uso.