Andrew Collier
Wed, 21 May 2008 09:10:13 -0700
Hi, Well - at least, any of the things you can ever change, yes! screen on/off, border colour, palette, screen mode, ram page, etc. Early versions of SimCoupe didn't support these changes better than once per line. I remember Allan (or was it Simon?) telling me he had never realised that the E-Tunes player from Fred 63 and on, even had a scrolly message - because at the time, SimCoupe wasn't able to display it. > Also, one further question: am I right to think that the Sam has no > means of producing interlaced video? Correct. Always non-interlaced (despite various examples on Fred of flickery pictures which purported otherwise). Andrew On Wed, May 21, 2008 at 04:36:34PM +0100, Thomas Harte wrote: > Literally anything? On many of the machines I have written emulators > for, most things are usually completely changeable but some things are > loaded internally — especially on any machine that has a variable > screen start address. > > Also, one further question: am I right to think that the Sam has no > means of producing interlaced video? > > On Wed, May 21, 2008 at 3:58 PM, Andrew Collier <[EMAIL PROTECTED]> wrote: > > On Wed, May 21, 2008 at 03:16:07PM +0100, Thomas Harte wrote: > >> If you interrupt routine is small, could you not also just switch off > >> the first one or two scanlines of your display, and even grab a few > >> extra cycles out as a result? Or can you not enable and disable the > >> display per scanline? > > > > Hi, > > > > You could, yes. You can alter pretty much anything about the screen on a > > line-by-line basis - and if you're very careful, during those lines in the > > screen area itself! For example, MMENOdemo 1 part 2 (on Fred 60) changes the > > screen page during the raster; repeatedly switching between foreground and > > background screens to draw lit and unlit rectabgles - which togehter form a > > scrolling message. > > > > Various other programs switch between mode 4 and mode 3, to get high > > resolution in a certain area of the screen - Edwin Blink's menu on Blitz > > (issue 6, was it?) and David Laundon's Fred menu come to mind. > > > > Anyway - in this particular case I wanted to display the whole screen; and > > in > > the case of one or two scanlines, it probably takes longer to set up the > > line > > interrupt handling, than you save by having the screen turned off. > > > > Cheers, > > Andrew > > > > -- > > --- Andrew Collier ---- > > ---- http://www.intensity.org.uk/ --- > > -- > > r<2+ T<4* cSEL dMS hEn/CB<BL A4 S+*<++ C$++L/mP W- a-- Vh+seT+ (Cantab) > > 1.1.4 > > -- --- Andrew Collier ---- ---- http://www.intensity.org.uk/ --- -- r<2+ T<4* cSEL dMS hEn/CB<BL A4 S+*<++ C$++L/mP W- a-- Vh+seT+ (Cantab) 1.1.4