Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.csd.uwm.edu!gem.mps.ohio-state.edu!tut.cis.ohio-state.edu!ucbvax!unisoft!bdt!bms From: bms@bdt.UUCP (Vance Chin) Newsgroups: comp.sys.atari.st Subject: Re: Hard Drive Speeds Message-ID: <113@bdt.UUCP> Date: 16 Aug 89 02:02:53 GMT References: <1275@blackbird.afit.af.mil> <29194@pbhya.PacBell.COM> <399@wet.UUCP> <676@opal.tubopal.UUCP> <411@wet.UUCP> Reply-To: bms@bdt.UUCP (Vance Chin) Organization: Berkeley Microsystems, Oakland, CA Lines: 13 In article <411@wet.UUCP> logic@wet.UUCP (Henry Kwan) writes: > >I'm curious about the BMS-200 host adapter though. They claim that it >supports a 1.6MB/sec transfer rate but I always thought that the ST's DMA >bus limit was 1.33MB/sec. Or are they measuring it at the SCSI level? > The Atari DMA bus will handshake at 2 Megabytes/second, this assumes zero turnaround time between ack's and drq's and the DMA bus. The problem is that the DMA chip tends to modify the data at this rate ( only a slight problem :-) ). The next step down is 1.6MB/sec due to the clock rates. Vance Chin