jtara@m2-net.UUCP (Jon Tara) (05/19/88)
A while back, in a discussion of ESDI controllers, someone mentioned that Adaptec had a controller that was supposed to get close to the theoretical maximum rate out of the drive. I had an OMTI, and wasn't happy with it's abysmal performance (about 500k/sec on corets27) so I decided to give the Adaptec a try. I'm happy to report that the Adaptec ACB-2322 is getting just over 1MB/sec on corets27 with a CDC WrenIII at 36 sec/track. This is on a 20mHz 386 using the C&T chipset. It also does very well with blocks smaller than the corets27 default of 64K - it generally does better than 700k/sec for block sizes of 24K and up, better than 500k/sec from 7k to 24k, 300k/sec at 4k blocks, 150k/sec at 2kblocks, and 73k/sec for 1k blocks. (Use the b:xxx option for corets27 - I'd like to see figures for other controllers...) The ACB-2322 controls two ESDI drives and two floppies. It's $236, and available through Hamilton/Avnet. Another model, the ACB-2320, is available without the floppy controller. These models are, according to Adaptec, *completely compatible with the AT controller from IBM*, and do not require a BIOS extension or special Xenix driver or Xenix version. There is an on-board BIOS extension, but it's used only for formatting and volume control. The on-board BIOS, along with a device driver (which, rather than being supplied on disk, is resident in the PROM, and *dumped to disk* from a menu choice - weird, but you don't have to worry about misplacing the disk...) supports multiple DOS volumes under DOS 3.1 or 3.2. Users of 3.3 can, of course, use the built-in multiple partition support. During formatting, it reads the drive parameters AND defect list from the disk, permits entry of additional defects, and does a worst-case data write/read just to make sure. (Which would have made things pretty smooth, except that the OMTI had previously managed to wipe-out the defect list on most of the surfaces - the OMTI doesn't know about recorded defect-lists.) I breifly considered the Western Digital 1007, but was disuaded by the higer price (almost $400), Western Digital's own statement regarding throughput (70-80% of maximum), and conflicting statements from various Western Digital technicians regarding compatibility. . I suspect that there are other truely high-performance controllers on the market that work even better than the Adaptec 2322 (elevator seeks, a large cache, etc. would be nice), but at $236, it's an undeniable bargain that does what it's supposed to do. -- jtara%m-net@umix.cc.umich.edu ihnp4!dwon!m-net!jtara "You don't have to take this crap. You don't have to sit back and relax." _Walls Come Tumbling Down_, The Style Council