Date   : Tue, 01 Aug 2006 14:52:12 +0100 (BST)
From   : Steve Fewell <kranser@...>
Subject: Re: Advanced BASIC and copros

Thanks for your answer. So the Service code always
runs in the I/O processor, and will not overwrite the
Tube copy.

> The patched ROM? I though Advanced BASIC used the
> original, ie
> *unpatched* BASIC, and modifed the code in RAM on
> the language
> side of the Tube.
Yes, it does. It copies the original HIBASIC ROM
accorss the Tube to &B800-&F7FF and patches sections
of it from &A800-&F7FF with the ABASIC specific code.

So, I should have said RAM, but the patched RAM
version does still have a ROM header (even though it
will not be referenced  by the MOS).

Steve.

--- Jonathan Graham Harston <jgh@...>
wrote:

> Steve Fewell <kranser@...> wrote:
> > The patched ROM makes use of a new OSWORD call
> (&B2)
>  
> The patched ROM? I though Advanced BASIC used the
> original, ie
> *unpatched* BASIC, and modifed the code in RAM on
> the language
> side of the Tube.
>  
> > My question is, what happens when the new OSWORD
> call
> > is made from the patched ROM (which does happen)?
> Will
> > the original ROM be loaded accross the Tube and
> > overwrite the new patched ROM?
>  
> >From the ROM (ie, the I/O processor) or from the
> Language? In
> either case, the I/O processor will call the ROM's
> service entry
> and the ROM's service handling code will deal with
> the OSBYTE.
> Whether that OSBYTE is a call to copy something
> across the Tube
> will determine whether anything is copied across the
> Tube or not.
>  
> All service routines are executed in the I/O
> processor; a service
> routine is not a language, it's a service routine.
>  
> -- 
> J.G.Harston - jgh@... -
> mdfs.net/User/JGH
> There are three food groups: brown, green and ice
> cream.
> 
> 



               
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