Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!utgpu!water!watnot!watmath!clyde!cbatt!ihnp4!ptsfa!lll-lcc!ames!ucbcad!ucbvax!nrl.arpa!neri%nrl.DECnet From: neri%nrl.DECnet@nrl.arpa.UUCP Newsgroups: comp.sys.atari.st Subject: (none) Message-ID: <8704071218.AA05543@ucbvax.Berkeley.EDU> Date: Tue, 7-Apr-87 08:11:00 EST Article-I.D.: ucbvax.8704071218.AA05543 Posted: Tue Apr 7 08:11:00 1987 Date-Received: Fri, 10-Apr-87 04:36:17 EST Sender: daemon@ucbvax.BERKELEY.EDU Reply-To: "NRL::NERI" Distribution: world Organization: The ARPA Internet Lines: 38 re: laser printers I admit that I may have been hasty in stating that a bitmap is necessary for a laser printer (as I have been reminded more than once). However, because of the mechanical nature of the laser printer (a photocopier with a laser light input) the image must be available at the rate required by the printer. Thus the full description of the page to be printed must be 'local' to the processor feeding the laser. Either the processor must be able to generate the dots for the laser on the fly (a question of processor speed and local memory) or it must form the bitmap and then stream it to the laser. For some applications, the bitmap is a very useful solution to the problem. In doing Tektronix 4010/4014 emulation, any portion of the page can be written at any time. So, constructing a bitmap from the incoming move/draw commands is easier than than reprocessing the commands for each local pass or band of laser printing. However, for some things like ASCII text it makes sense to do it on the fly, as you don't write to the same place again. It comes down to matter of what processor capabilites (read expense) are put into the laser printer. The argument for doing every thing on the fly is that as soon as the page is formed, printing can start without waiting for the bitmap to be finished. With memory getting cheaper, one can have enough memory for two bitmaps, and be printing the image from one, while forming the image for the next page in the other. The "full" capability 'on the fly' laser printers are not cheap. The 8 page per minute Talaris and Imagen printers are in the 8k$ range. Most of that cost is for the intelligent printer electronics. The higher cost for faster or higher volume printers goes for a large part to the increased cost of the photocopier engine. As an example at the low cost end, the differences between the capabilities of different model of HP Laserjets to do graphics (150 dpi vs. 300 dpi full page) is directly related to the size of the bitmap that the printer can hold. Jess Neri Neri@nrl.arpa DISCLAIMER: I'm on my own on this too! "Just remember, no matter where you go, there you are." - Buckaroo Bonzai ------