Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!rutgers!topaz!eric From: eric@topaz.RUTGERS.EDU (Eric Lavitsky) Newsgroups: comp.sys.amiga Subject: Re: Hard disk through parallel port Message-ID: <8088@topaz.RUTGERS.EDU> Date: Mon, 22-Dec-86 21:33:51 EST Article-I.D.: topaz.8088 Posted: Mon Dec 22 21:33:51 1986 Date-Received: Tue, 23-Dec-86 00:32:59 EST References: <634@hp-sdd.HP.COM> <1121@cbmvax.cbmvax.cbm.UUCP> <1527@ulysses.ho <2241@well.UUCP> Organization: Rutgers Univ., New Brunswick, N.J. Lines: 76 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: .>>>George Robbins (cbmvax!grr) Writes: .>>>Well, since there is no DMA support available for the Parallel Port, the .>>>actual data transfer part of the disk activity will be slower than a DMA .>>>type disk controller attached to the Expansion Bus. .>> .>>A bit of clarification here: George is correct, but: The only thing DMA .>>really buys you on the Amiga currently, is the fact that data trasnfers .>>don't interrupt the CPU. The maximum *actual* throughput for current DMA .>>vs. non DMA disks is currently limited by AmigaDOS, which can only chug .>>through about 35K/Sec. So, a disk on the parallel port, if designed correctly .>>will get you at least close to that limit and a DMA disk cannot surpass .>>that limit (at least not the ones that currently exist). Of course, if .>>you're not using AmigaDOS, that's another story... .>> .>>Eric > >Eric, > >I know that you are int the know, but in this case you are incorrect. the DMA >is much faster than what can happen on the parallel port. What transpires on >the expansion bus if difficult to get used to, although one adapts to the speed >in time and cna await the 2 to 3x speed improvement in the DOS that is coming. Well Jim, thank you - I know that you are in the know as well, and I think that InfoMinder is a great product, but... I never suggested that there was any DMA on the parallel port, or that the parallel port was as fast as the expansion bus. I still stand behind what I said. Perhaps a little further clarification is necessary... Imagine the following: you drive a Lamborghini :-). Of course, this car can outpreform just about any other car in America. Bring the car onto your average American highway however, and you will be forced to do about the same speed as the other cars on the road (though it may take you less effort). Why?, because the American roads are so bad they limit you to a slower speed (this is a documented fact :-)... So currently (and I underline that word), the bottleneck is AmigaDOS (as you even pointed out). Yes, it is good news that Tim King has finally done something about it, and when it's finally generally available (how long do you think it will take?), there will be no question that DMA disks are oodles faster than any other. But for now, everyone has to travel on the same road (note that I'm still talking about throughput through AmigaDOS, *not* raw data transfer rates). So: Parallel port 30K/Sec => AmigaDOS =>User ~= Expansion Bus 10Mbit/Sec => AmigaDOS =>User Does that explain my point better? Another important thing to mention is that Phil's news about Tim Kings' fixes was news to me after I sent my message out... so all this may be moot (when the improvements see the light of customers' hands)... >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? :-) >Amiga will be the future, espiecially if C-A realizes it. > >-Jim Becker >Terrapin Software Eric (I hate inews) Lavitsky -- ARPA: LAVITSKY@RUTGERS or LAVITSKY@RED.RUTGERS.EDU UUCP: ...topaz!eric ...hplabs!well!lavitsky ...ulysses!eric