Msg: 1155 *Conference*
12-23-91 18:19:21
From: ERIK FRANCIS
To : ALL
Subj: MODEL 100 GRAPHICS?
Where in Model 100 memory is the screen data located? Where (or how) does it know when a certain group of pixels is on or off? I know the text memory is located from FE00h to FF40h, but how about the pixels? I saw a rather strange algorith that was designed to detect whether a given pixxel was on or off . . . I can't say I understood it, though. It was in the game GRID.BA, but the author claimed it had to blink the cursor. It was: PRINTCHR$(27)"P";:PRINT@INT(X/6)+40*(Y/8),;:Z=SGN((2^(YMOD8))AND PEEK((XMOD6)-20)):PRINTCHR$(27)"Q";:RETURN The subroutine, according to the author, sets the pixel located at (X, Y) and returns Z = 0 if the pixel is "on" (dark) or Z = 1 if it is "off" (light). I can understand that it's doing, but why in the world must it be done in such a roundabout way?