Hi Christian, On 11/6/12 1:15 PM, 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. > The ROMs are -02's. The screen slowness is normal. You'll find a disassembly of the KERNAL ROM here: http://www.von-bassewitz.de/uz/oldcomputers/p500/rom500.s.html The KERNAL calls special routines whenever it needs to write to the VIC-II registers (wrtvic), screen RAM (wrtvram), or color RAM (wrtcram). As a result, the screen is quite slow. These routines were to work around hardware instability. I've never read an explanation of the specific issue. Recently I have been experimenting with my P500. I have a program that writes directly to the screen RAM and seems to work. I've read of others doing the same with success. It may be that not all P500 machines have the issue or that it only occurs under some conditions. Regards, Mike -- Mike Naberezny (firstname.lastname@example.org) http://6502.org Message was sent through the cbm-hackers mailing listReceived on 2012-11-06 22:00:43
Archive generated by hypermail 2.2.0.