chip@tct.uucp (Chip Salzenberg) (01/03/91)
Scrolling can be a big CPU time drain on IBM PC architectures, where the video RAM is v-e-r-y slow to access. So to speed up scrolling in a terminal emulator we use in house, I shadow the screen with normal RAM, with a rotating "top line" index. With this setup, scrolling is as simple as bumping the top line index and copying from normal RAM to screen memory. And each word of screen memory need not be read, only written, thus significantly speeding up scrolling. There's also the hack that updates the fast shadow screen but stops updating the real slow screen when the serial input buffer gets almost full... -- Chip Salzenberg at Teltronics/TCT <chip@tct.uucp>, <uunet!pdn!tct!chip> "Please don't send me any more of yer scandalous email, Mr. Salzenberg..." -- Bruce Becker