Commodore 128 Alive!

Commodore PET => Commodore PET => PET tips & tricks => Topic started by: Blacklord on July 28, 2009, 07:22 AM

Title: PET speed-up
Post by: Blacklord on July 28, 2009, 07:22 AM
You can speed up the PET dramatically just by typing POKE 59458, 62
Title: Re: PET speed-up
Post by: Shaun_CCC(UK) on August 01, 2010, 07:44 AM
On a real 80xx PET this seems to mess the screen up (I have BASIC 4.0) so be warned.

Regards,

Shaun.
Title: Re: PET speed-up
Post by: Blacklord on August 01, 2010, 05:21 PM
Quote from: Shaun_CCC(UK) on August 01, 2010, 07:44 AM
On a real 80xx PET this seems to mess the screen up (I have BASIC 4.0) so be warned.

Regards,

Shaun.

Works on a CBM 2000 (4k PET).
Title: Re: PET speed-up
Post by: Shaun_CCC(UK) on August 01, 2010, 06:39 PM
How do I determine the hardware then please? Something like:

IF PEEK(xxxxx)=xxx THEN POKE.....

This would be helpful for my 4K game should I have enough space to get this line in.

Regards,

Shaun.
Title: Re: PET speed-up
Post by: wte on August 03, 2010, 03:53 AM
Gasch!

That's the Killerpoke!

Read more: http://www.6502.org/users/andre/petindex/poke/index.html

Regards WTE

PS: I'm also searching for a simple peek to check if a poke 59458, 62 is "required" or "incongruous".
Title: Re: PET speed-up
Post by: carlsson on August 19, 2010, 08:20 AM
I don't have the answer, but somehow I think you can program the VIA to read a status register from the CRTC chip if present? I suppose on an older, non-CRTC PET you would get zero or garbage if it is possible to read the CRTC at all. This page - also by André - is fairly technical but it could be worth looking into.

http://www.6502.org/users/andre/hwinfo/crtc/index.html (http://www.6502.org/users/andre/hwinfo/crtc/index.html)
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