Xref: utzoo comp.periphs.scsi:2761 comp.sys.ibm.pc.hardware:9236 Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!think.com!zaphod.mps.ohio-state.edu!mips!atha!aunro!ersys!bking From: bking@ersys.edmonton.ab.ca (Barry King) Newsgroups: comp.periphs.scsi,comp.sys.ibm.pc.hardware Subject: Re: How much faster is a 16 bit SCSI Card than the ST02? Message-ID: Date: 31 May 91 12:57:30 GMT References: <3167@ria.ccs.uwo.ca> Organization: Edmonton Remote Systems, Edmonton, AB, Canada Lines: 30 I have both an Adaptec 1540B and a DPT PM2001/95. I now use the DPT board only. I have it connected to a Conner CP3200F, 200 Mb SCSI-2 drive. In comparing the Adaptec to the DPT, I had some interesting results. According to Core tests, for what they're worth, the DPT delivered faster seek times (18.1 msec for the DPT vs. 19.2 for the Adaptec). I attribute this to the fact that the DPT uses a faster processor (MC68000, 10 MHz) and is a full 16-bit board meaning that all data paths are 16 bit. This is not (I believe) the case for the 1540B - it uses and 8 bit processor. As to throughput, the DPT was slightly faster but not significantly so. I would get about 785 Kb/sec for 64 Kb reads on the DPT, slightly lower for the Adpatec. Again, this is probably due to the faster CPU on the DPT (therefore lower SCSI overhead perhaps). I don't reallt trust Core for measuring the throughput. I think something funny is going on because others with the same Conner drive have measured higher throughput. The machine I'm using is a 386/33 ISA bus jobbie with an AMI BIOS. So many things can affect disk I/O. I've stopped worrying about the numbers. When I reduce the blocking factor for Core I can push the throughput up past the 1.5 Mb/sec range. I'm sure this is due to the fact that the Conner has a 64 Kb read-ahead cache on it. Anyway, I think it's worth the 16 bit SCSI HBA for fast machines, especially since a 386/33 (and maybe even slower machines) spend a lot of time waiting for ISA bus activity to complete. The Adaptec is a decent board - so is the DPT (I really like it). I'm sure that there are other boards out there that perform equally as well. Barry King bking@ersys.edmonton.ab.ca Edmonton Remote Systems: Serving Northern Alberta since 1982