Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!mimsy!cvl!umd5!louie From: louie@sayshell.umd.edu (Louis A. Mamakos) Newsgroups: comp.sys.amiga Subject: Re: Hard disk through parallel port Message-ID: <1404@umd5> Date: Tue, 23-Dec-86 11:56:08 EST Article-I.D.: umd5.1404 Posted: Tue Dec 23 11:56:08 1986 Date-Received: Wed, 24-Dec-86 00:04:00 EST References: <634@hp-sdd.HP.COM> <1121@cbmvax.cbmvax.cbm.UUCP> <1527@ulysses.ho <2241@well.UUCP> <8088@topaz.RUTGERS.EDU> Sender: uucp@umd5 Reply-To: louie@sayshell.umd.edu (Louis A. Mamakos) Organization: University of Maryland, College Park Lines: 28 In article <8088@topaz.RUTGERS.EDU> eric@topaz.RUTGERS.EDU (Eric Lavitsky) writes: >In article <2241@well.UUCP>, bj@well.UUCP (Jim Becker) writes: >.>In article <1527@ulysses.homer.nj.att.com> eric@ulysses.UUCP (Eric Lavitsky) w >rites: >>The Parallel port doesn't have DMA, but the serial port does. Noone has tapped >>this yet though. It will be inconsiquential though, when the Pal Jr comes out >>there will be a new standard that will take a while for the human to get >>used to, especially with InfoMinder Plus. > >Yes, but to tie up the serial port with a hard disk would be a very >big mistake - one often wants his disk available while online with >another host, you could always wait for the printer, right? :-) > Hmmm.. from all that I've seen, the serial port doesn't do DMA. It just generates interrupts. Both the hardware manual and disassembly of the serial driver seem to bear this out. It's a real shame it doesn't. In any case, another issue to examine when considering a DMA disk vs. an interrupt driven one is the effect on the rest of the system. Even though the bandwidth to the disk is the same, the DMA design should all the CPU time to service other tasks in the system. The non-DMA version will consume more CPU resources to get its job done. Ain't this multitasking just grand? A computer that can walk and chew gum at the same time! Louis A. Mamakos WA3YMH Internet: louie@TRANTOR.UMD.EDU University of Maryland, Computer Science Center - Systems Programming