Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!bloom-beacon!mit-eddie!rutgers!rochester!pt.cs.cmu.edu!PULSAR.FAC.CS.CMU.EDU!moore From: moore@PULSAR.FAC.CS.CMU.EDU (Dale Moore) Newsgroups: comp.lang.postscript Subject: ideas on onboard processors Message-ID: <3068@pt.cs.cmu.edu> Date: 21 Sep 88 16:50:46 GMT Sender: netnews@pt.cs.cmu.edu Organization: Carnegie-Mellon University, CS/RI Lines: 49 Here are some of my thoughts about onboard vs outboard PostScript. Outboard is the way most all PostScript printers work today. The processing is done out on the peripheral rather than in on the general purpose processor. Some folks concern is that the extra bandwidth necessary to ship the image to the printer will be a bottleneck. Ethernet and other mediums operate at 10mps. With a large number of vendors building hardware for such networks, it is entirely feasible to build inexpensive Ethernet (rather than serial line or Appletalk) printer. Several folks have already done so. At an effective usage of 20% of the network bandwith, 300 dots per inch, 1 bit per dot, that comes down to less than 5 seconds per page. With the advent of FDDI and other networking technology, the time necessary to ship that many bits over a standard cable will decrease. Many of todays PostScript printers have more memory and faster CPU inside the printer than the general purpose machine that is generating the PostScript and sending it to the printer. The analogy is that the slave peripheral has more potential power than the master. That is something that seems entirely backward to me. Much of the time, a PostScipt printer (and its CPU and memory) are sitting idle. If the CPU and memory were available to the user to perform other computing tasks when the printer was not in use, this would result in a more effective use of the hardware. Multi-Processors with multi-processing systems are commercially available. Sequent, Balance and Next are systems that produce (or will shortly) commercial multi-processor systems. The hardware that is typically devoted to the task of changing page description languages into bitmaps could instead be part of a multi-processor operating system. Upon demand a single processor could be devoted to doing its traditional task of turning a page desciption language into bitmaps, and shipping those bitmaps to the printer. But when the printer was not needed for that task the processor could be devoted to performing other tasks as a normal part in the multi-processor system. The time necessary to ship images to a printer will only decrease as networking technology develops. More effective use can be made of the hardware if the hardware is part of a general purpose system, rather than devoted to supporting a complex function inside a peripheral. Dale Moore Computer Science Carnegie Mellon University