Date   : Mon, 04 Mar 1996 21:47:06 +0000 (GMT)
From   : Tom Seddon <T.W.Seddon@...>
Subject: Re: BBC: Radical rethinks! :-)

On Mon, 4 Mar 1996, Robert Schmidt wrote:

> One thing I'd consider implementing in an emulator is more OS hooks -
> especially for graphics functions like line, character and polygon drawing.
> If these were executed on the host system instead of through emulated 6502
> code in the OS, some programs would really fly (especially BASIC programs).

I debated whether to do this myself for OSWRCH etc, but it would be a lot 
of hassle. For my Atari ST emulator I tried writing a complete OSWRCH 
implementation, but after a while it just got too hard. I reckon that for 
most games it wouldn't make much of a difference anyway since they use 
their own routines.

I suppose, though, that if you had enough hooks and hacks you'd have your 
own (very fast) OS 1.2 clone, and you wouldn't have to use the original 
Acorn ROMs! (Then all we need is a freeware BBC BASIC and everything 
would be fine!)

> Does Elite use the standard line drawing functions, or does it provide its
> own drawing code?

I suspect that Elite uses its own line drawing routines, to get the speed.
Furthermore the screen is 256 bytes in width (Rather than 320) so the
normal OS ROM graphics routines wouldn't work. I suppose that the
multiplication tables used by the OS could be changed, but then it might 
not work with other operating system versions. I don't know whether Elite 
(standard) works on the B+ (or whether the B+'s operating system is 
sufficiently different for this to be a problem).

And as a suggestion for your ftp site, why not check for ftp accesses 
coming from xx.acorn.co.uk and hide the ROMs from view if necessary?! :-)

--Tom
 
    |     ** Tom Seddon **	  E-mail: T.W.Seddon@...
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