Re: P500

Mike Naberezny and I also discovered what appears to be a bug in the BLOAD command. It seems the p500 is unable to bload into bank 15. Either that or the bload parameters are different on the p500 as compared to the b series.

Steve


On Nov 6, 2012, at 4:53 PM, Steve Gray <sjgray@rogers.com> wrote:

> Hi Ullrich,
>  
> You got your reply in while I was writing... nice. And thanks for the disassembly listing!
>  
> Someone definitely needs to fix that kernal ;-)
> Steve
> 
> From: Ullrich von Bassewitz <uz@musoftware.de>
> To: cbm-hackers@musoftware.de 
> Sent: Tuesday, November 6, 2012 4:40:51 PM
> Subject: Re: P500
> 
> 
> Hi!
> 
> On Tue, Nov 06, 2012 at 10:15:04PM +0100, Christian Dirks wrote:
> > The screen scrolling seems very slow to me.
> > Since I haven't seen a working P500 before, I don't know, if it is
> > alwas that slow.
>                                                           
> Scrolling (and video output in general) is slow on the P500. Commodore seems
> to have had issues with accessing the VIC and the video/color RAM, so they
> used rather complex write routines. See the routines wrtvic, wrtvram and
> wrtcram in the ROM listing:
> 
> http://www.von-bassewitz.de/uz/oldcomputers/p500/rom500.s.html#AALV
> 
> Fortunately the routines to write the RAM are called via vectors:
> 
> http://www.von-bassewitz.de/uz/oldcomputers/p500/rom500.s.html#AAL5
> 
> Since most versions of the P500 don't have the access problems, one can change
> the write vectors to point to simple write routines instead of the complex
> original ones. This will speedup the output considerately.
> 
> > The ROMs are -02's.
> 
> These are the latest ROMs known to exist. At least to me:-)
> 
> Regards
> 
> 
>         Uz
> 
> 
> -- 
> Ullrich von Bassewitz                                  uz@musoftware.de
> 
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> 
> 


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