ehs@src.dec.com (Ed Satterthwaite) (04/08/91)
In a previous posting Ordania-DM@cup.portal.com (Charles K Hughes) writes: > When a gr.0 screen is scrolled, only 1k has to be moved. When a gr.8 screen > is scrolled, 8k has to be moved. This movement is the real killer. ... > The only adequate reason for 1200 only term programs is because the authors > just couldn't figure out how to get 2400 to work. It's possible, but > not worth the effort (to the authors in any case). I think the latter is the real problem. The Atari display commands and display lists partition the screen into horizontal bands. This is a real pain for some applications, but it's perfect for scrolling. Just use one display command per line and scroll by updating the display list -- a very fast operation compared to moving all the bits on a gr.8 screen. I once modified a VT52 emulator written in ACTION! to use this technique and it easily kept up with 2400 baud. I believe Kermit65 uses the same technique. A serious problem with an 80 x 24 display is that a standard Atari 8-bit doesn't provide enough pixels to allow a decent looking rendition of the character set, at least in my opinion. The VT52 program used characters that were quite legible on my monitor (a 1702) but had all the charm and grace of an OCR font. Perhaps that's why authors haven't worked very hard to support such displays. Ed Satterthwaite ehs@src.dec.com
jeff@crash.cts.com (Jeff Makey) (04/08/91)
In article <1991Apr7.103154.27547@src.dec.com> ehs@src.dec.com (Ed Satterthwaite) writes: >I once modified a VT52 emulator written in >ACTION! to use this technique and it easily kept up with 2400 baud. I did the same thing, and I have been using my modified version of VT52B.ACT at 2400 baud for several years. There is no flow control, but the R: handler that comes with the P:R: Connection has a 128-byte buffer that helps. I have only recently discovered that the program has trouble keeping up if lots of short lines are printed rapidly, but I'm sure that the scrolling speed could be improved if it were really necessary. :: Jeff Makey Department of Tautological Pleonasms and Superfluous Redundancies Department Posting from my temporary home at ... Domain: jeff@crash.cts.com UUCP: nosc!crash!jeff