Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uwm.edu!ogicse!decwrl!adobe!heaven!glenn From: glenn@heaven.woodside.ca.us (Glenn Reid) Newsgroups: comp.lang.postscript Subject: Re: Bitmap of PostScript code.. Message-ID: <145@heaven.woodside.ca.us> Date: 21 Feb 90 16:45:51 GMT References: <1990Feb14.041704.14844@athena.mit.edu> <2761@bacchus.dec.com> <30006@sparkyfs.istc.sri.com> <17975@rpp386.cactus.org> <1990Feb19.172134.12850@intercon.com> <144@heaven.woodside.ca.us> Reply-To: glenn@heaven.UUCP (Glenn Reid) Organization: Skyline Press, Woodside CA Lines: 37 In article jaap+@andrew.cmu.edu (Jaap Akkerhuis) writes: + Suppose you have a (hypothetical) fast printing engine, say 100 pages a + minute for raw speed. Normally you have one postscript engine, and now + look at the speed you will get in the end. Well, since postscript is + interpreted, fonts might not be in the cache etc, it takes a while for + the pages to be processed. What is really frustrating is that you now + know that the printer can run on 100 pages a minute (you checked this + with fooling around with #copies) and you actually will see 30 pages a + minute or so. It is easy to imagen a setup where you have a couple of + processors with (quite) some disc space. Each individual job is directed + to a different proccessor, the bitmaps are stored to disk and the + printer can be fed with the bitmaps at full speed (after which the + bitmaps are removed) with the bitmaps of one job while the other jobs in + the queue are calculated. Of course, slightly more complicated setup can + be thought of. Note that I don't propose to take the bitmaps and store + them to a general purpose machine for turning them into group 3 encoding + or other uses. I would consider above described setup as a black box, + just as I consider my current printer as a (whatever colour painted) + black box. Are you sure you can feed bitmaps to the marking engine that fast? I'm not sure, but I doubt that the bandwidth on most disks would even come close. Given a 300dpi frame buffer, which is roughly 1 megabyte of data, you would have to be able to feed 100 megabytes a minute. Maybe that's possible. What is the bandwidth to/from most disk drives, anybody know? I think you just need a faster controller, or perhaps better-formed PostScript code, to really get 100 ppm. Maybe the disk scheme would work, but I vaguely remember people saying that it wouldn't even work on an 8 ppm printer, but maybe with some compression/decompression scheme you could do it. In any case, you raise a good point. The bitmaps in your example are more like a "cache", an optimization. They still have only one purpose, to be fed to the marking engine for which they were rasterized. Glenn Reid