valdis@sun.mcs.clarkson.edu (07/17/88)
Hmm. Maybe these wizards are cleverer than I, but I've been in this business as either a student or a professional for close to a decade now, so I'll voice my opinion... :-) Somebody proposed that we use a downloadable 256-char font with appropriate pixel definitions to cover all possible bit patters. I've USED such a beast - it's called an IBM 3270 Programmable Symbol Set. OK. So we're using 9x11 pixmaps. (if not 9x11, then something else equally sized 9x13, 11x15 - argument still holds). Hmm. 99 pixels. That gives us a LOT of possible pixmaps - like 2**99 (each pixel can be on or off, count in binary - we're all wizards here, right? :-) Somehow I don't think we're gonna get it to fit. And of course, that's the reason the IBM solution is ugly. If you ever see the 'coyboy hat' demo of Sas/graph, you can SEE where they cheated a bit and MOVED THE LINES around so they could re-use an already defined character. They only have like 3,000 graphics slots they can download. And they STILL have to cheat. The biggest thing you can fit in a 256-char font and cover all bases is if you have a 2x4 char font. That gives you 8 pixels that need 2**8 = 256 different pixmaps for coverage. A 3x3 loses, as that's 9 pixels and 512 pixmaps. OK - all you OLD TIMERS out there - has ANYBODY ever seen a terminal that gave you a ** two by four ** character matrix?? *AND* downloadable fonts? *AND* didn't have a video generator that forced one blank pixel between chars and two between rows like a lot do, so you have all-points-addressable? I'm amazed that this discussion has gone this long without a reality check. Personally, I'll wait for an X11 port to something a bit more powerful than a terminal - like a Mac II. Until then, I'll use 'screen' on my TVI 950 when I call from home. Valdis Kletnieks Sr. Systems Programmer Clarkson University
jbs@eddie.MIT.EDU (07/17/88)
In article <16524@brl-adm.ARPA> valdis@sun.mcs.clarkson.edu writes: >Somebody proposed that we use a downloadable 256-char font with appropriate >pixel definitions to cover all possible bit patters. I never proposed such a thing. Please re-read my article. (back from re-reading so soon?) Now, note that I did not say anything about a downloadable font, nor did I say that I wanted to access every possible bit pattern. Each character on the terminal would be dealt with, by the server, as one "pixel"--one that can contain some number of different values, not that unlike a color display. The server would not display a character by painting it pixel-by-pixel; it would simply set one pixel to the correct value. (again) The goal here is not to do graphics on a character terminal. It is to do characters on a character terminal--using a consistent, (roughly) device-independent, network-transparent protocol: X. Jeff Siegal
lyndon@ncc.Nexus.CA (Lyndon Nerenberg) (07/17/88)
In article <16524@brl-adm.ARPA> valdis@sun.mcs.clarkson.edu writes: > [ ... ] OK - all you OLD TIMERS out there - has ANYBODY ever seen a terminal >that gave you a ** two by four ** character matrix?? *AND* downloadable fonts? >*AND* didn't have a video generator that forced one blank pixel between chars >and two between rows like a lot do, so you have all-points-addressable? OLD timer, indeed! :-) A few years back, I had the misfortune of owning a Kurzweil 4000 OCR system. The operator console would display the text as it was recognized, with questionable characters highlighted. You could get a graphic display of the character as it appeared on the page via one of the function keys. I discovered (accidently) one day that the system displayed this graphic by mapping the raster image into a series of ASCII characters representing the various combinations of "bitmap cells." I don't know how many fonts this took (or what the cell size was) however they had to have mapped the entire range of cells in, as the image was a complete one in all respects. The terminal was manufactured by Microterm. I don't know if Microterm or Xerox were responsible for the modifications... -- {alberta,pyramid,uunet}!ncc!lyndon lyndon@Nexus.CA