Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!portal!cup.portal.com!truett From: truett@cup.portal.com Newsgroups: comp.dcom.lans,comp.sys.ibm.pc Subject: Re: IBM PC/AT DMA loses (was Re: PC LAN Comparison) Message-ID: <1651@cup.portal.com> Date: Sat, 28-Nov-87 03:35:54 EST Article-I.D.: cup.1651 Posted: Sat Nov 28 03:35:54 1987 Date-Received: Mon, 30-Nov-87 01:43:56 EST References: <2070@killer.UUCP> <1020@kodak.UUCP> <155@tic.UUCP> <261@kaos.UUCP> <1560@cup.portal.com> <162@tic.UUCP> Organization: The Portal System (TM) Lines: 25 Xref: mnetor comp.dcom.lans:970 comp.sys.ibm.pc:10576 XPortal-User-Id: 1.1001.2190 rulu@tic.uucp (Dragos Rulu) asks if there are any examples of commercial hardware products that use the dual-ported memory approach to bulk data movement into and out of an IBM PC/AT. There are many, but let me illustrate the preponderance of this method by looking at one situation where bulk data must be moved quite quickly -- laser printer interfaces. I know of at least four such interfaces that use some form of memory dual- porting to achieve high transfer rates: 1) the Tall Tree JLaser, 2) the Advanced Vision Research MegaBuffer, 3) the Cordata LBP interface, and 4) the AST Turbolaser interface. I believe the Laser Master also does this. Unfortunately, I am not very familiar with the Hewlitt-Packard LaserJet interfaces. This problem of moving data to a fast printing engine quickly becomes most acute when bit-mapped graphics are involved. Why all of the laser printer manuafacturers haven't come out with a SCSI interface is beyond me! It has the throughput and would allow the printer interface to share a slot with other peripherals. Similar considerations would apply to input from image scanners. This surfeit of proprietary interfaces cannot be any good, in the long run, for the industry. I would note that most SCSI interfaces for the PC standard bus give the programmer the choice of DMA or PIO control of the transfer. Truett Smith, Sunnyvale, CA UUCP: truett@cup.portal.com