Path: utzoo!utgpu!watmath!clyde!bellcore!rutgers!att!whuts!homxb!homxc!rps From: rps@homxc.UUCP (R.SHARPLES) Newsgroups: comp.sys.ibm.pc Subject: Re: 1:1 interleaving MFM controllers Summary: Other experiences Message-ID: <4490@homxc.UUCP> Date: 7 Dec 88 14:49:53 GMT References: <11272@spl1.UUCP> Organization: AT&T Bell Laboratories, Holmdel Lines: 30 In article <11272@spl1.UUCP>, raj@spl1.UUCP (Robert Alan Johnson) writes: > ISSUE 1: NORTHGATE's contention that you can't do 1:1 > on MFM drives. > > ISSUE 2: Controller design approach. I have recently looked > at the OMTI 1:1 MFM controller and discovered that they use > a PIO (Programmed I/O) approach which has a firmware routine > dispatching the characters from the controller. When tested with > a 12MHz AT at 1:1 the throughput was awful. We then tried again with a > 20MHz AT. Results were still bad. When we discovered that we were running > in NON-TURBO mode. When we kicked the 20MHz machine into TURBO, the > disk throughput went up to over 750KB/Second, blowing away a PS2/70 with > an ESDI drive! On the AT&T 6386s we have here, a Western Digital WD1006-WAH 1:1 MFM controller is used with a Micropolis FH 70mb drive. The 6386 is running at 16mhz with one wait state. CORE TEST reveals a throughput of about 500Kb/sec which is almost the same as what we see with the Lightening Disk Caching program installed. What you are saying about high CPU horsepower required for 1:1 MFM throughput is probably being confirmed here because a 386 at 16mhz/1WS is similar in speed to a 20mhz 286. Russ Sharples homxc!rps NOTE: The above in NO WAY reflects the opinions of AT&T. These opinions are my own and the results of un-scientific and highly irregular analysis methods.