Path: utzoo!utgpu!watmath!clyde!att!pacbell!lll-tis!oodis01!uplherc!esunix!blgardne From: blgardne@esunix.UUCP (Blaine Gardner) Newsgroups: comp.sys.amiga.tech Subject: 2090A speed Keywords: I feel the need, the need for speed. Message-ID: <1106@esunix.UUCP> Date: 23 Nov 88 15:26:11 GMT Organization: Evans & Sutherland Computer Corporation Lines: 45 I've got one of the first A2090A controllers with a Seagate ST4096 hooked up to the ST506 interface. Diskperf consistantly returns maximum read speeds of 200K to 220K. This seems awfully slow for a DMA controller, especially since a couple of friends with the old, non-DMA, CLtd SCSI controller are getting 300K to 350K. One has an ST506 (really, a 5M ST506) with a SCSI- ST506 adapter, and the other has a 65M Seagate SCSI (I don't know the model number). Why would a DMA interface with a 28 mS drive be so much slower than a non-DMA interface with 40 and 85 mS drives? One possiblity is that I need to change the interleave from 1:1 to another value. But I was under the impression that the 2090A could handle data at full speed from the drive. If I do need to change the interleave, is it possible to just reformat one partition with a different interleave, or do I have to start from scratch with Prep? If interleave is the problem, I'd like to make trying different interleave values as painless as possible. What about buffered seek? This is a feature of the ST4096, and I understand that it's supposed to improve drive speed. Does the 2090A support this feature? On a slightly different subject, has anyone successfully formatted an ST506 drive that has more than 8 heads? My ST4096 is a 9 head drive, but I can only format with 8 heads, so I've got 9 meg going to waste. :-( I got some e-mail from Dale Luck saying that if the 2090A didn't work with more than 8 heads, a PROM swap would fix it. Dale offered to get the PROM to me, but I've been unable to make e-mail contact with him. Any help with getting the 9th head working would be greatly appreciated! For the record, this is an A2000, 3M RAM, A2090A, ST4096, WB & KS 1.3. The 2090A is in the slot nearest the CPU slot, and the 2M ASDG card is in the second slot. -- Blaine Gardner @ Evans & Sutherland 580 Arapeen Drive, SLC, Utah 84108 Here: utah-cs!esunix!blgardne {ucbvax,allegra,decvax}!decwrl!esunix!blgardne There: uunet!iconsys!caeco!pedro!worsel!blaine (under construction) "Nobody will ever need more than 64K." "Nobody needs multitasking on a PC."