Message-ID: <5889@uiucdcs.UUCP>
Date: Sun, 26-Feb-84 22:55:49 EST
Article-I.D.: uiucdcs.5889
Posted: Sun Feb 26 22:55:49 1984
Date-Received: Tue, 28-Feb-84 00:22:18 EST
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#R:tekig1:-154800:uicsg:7600013:000:1320
uicsg!mzp Feb 26 18:24:00 1984
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Whale, one thing you can do (speaking with WD2793 experience) is to issue
a read-address command. This waits for the next ID field and chunks back
six bytes indicating the track, sector, side, size, and CRC. You can use
this information to intelligently generate a request for the sector following
that one. This is just ad hoc thought, by the way. I don't know of any
software that actually takes advantage of this capability. I am personally
too lazy to write the drivers required to do track buffering, much less
anything this complicated.
As for intelligent controllers, the WD2790 series are the best that I
have come across. They have a built-in PLL data seperator for DD and
support 5"/8" drives. I have built a 4-disk 8" controller for an 8086
system that takes about 10 square inches of board space! This of course
presupposes an existing DMA device. DMA transfers are supported by the
279x. The NEC765/i8272 have some nice features, including a bit more
programmability and built-in 4-drive select and head load, but the Western
Digital controllers are unquestionably easier to use.
Hope that this at least provides you with a start in the right direction.
Let me know if you come across anything exciting.
Mark Papamarcos
pur-ee!uiucdcs!uicsl!uicsg!mzp