The problem with that is both 40 and 80 column screens are configured the same (as 40 column) since the 80-column circuitry does tricks to display 2 characters in the space of one.You can identify european vs north american (50/60 hz power) by looking at the timing registers, but not 40 vs 80. You could monitor for writes to screen ram >1024 to indicate 80 column. this would be done at initialization to clear the screen. Steve From: didier derny <didier@aida.org> To: cbm-hackers@musoftware.de Sent: Tuesday, February 27, 2018 6:30 AM Subject: Re: commodore 8032 vga / ports to monitor thanks for the informations I think I found a way to support from the original pet 2001 to the 8296 I'll configure initially for 40 columns (pet 2001) mode (color of the screen / level with trim on the board) then when I receive the crtc configuration I'll switch to the correct mode Le 25/02/2018 à 00:28, Mia Magnusson a écrit : > Den Sat, 24 Feb 2018 22:49:37 +0100 skrev didier derny > <didier@aida.org>: >> I guess that for my vga board, all I need to monitor >> >> is the write in CRTC (to reconfigure the screen emulated in the >> propeller) >> >> and the write in $FFF0 to detect when the screen or I/O area are >> shadowed by the 64k extension ? >> >> >> I've not seen anything else in PIA/VIA but I may have missed something >> >> for me the 8032 it's quite old... > There is the "killer poke" that turns the VSYNC detect input to an > output. On the oldest PETs the hardware did drive hard enough that this > didn't matter but it disabled the timing logic halting the cpu when > accessing video ram while video were displayed. On newer machines it > messes up VSYNC output. > > Don't know if there is any use emulating that behavior. > > P.S. if you want some ideas for feature creep you might want to have a > look at the various hires addons for PETs :) > Message was sent through the cbm-hackers mailing list Message was sent through the cbm-hackers mailing listReceived on 2018-02-27 15:00:02
Archive generated by hypermail 2.2.0.