Date   : Mon, 19 May 1986 17:51:22 mdt
From   : Pat McGee <jpm%a@LANL.ARPA>
Subject: Re: Need help w/old Altair HD controller

I worked on one many years ago.  I don't have any written
information left, but I could probably remember details if
you have questions.  You said you were totally mystified
by the controller.  It has 4 buffers on the board, and
when you read a sector, the data goes into the buffer.
You can then get the bytes one by one from the buffer
by sending read buffer commands.   This is excruciatingly
slow in BASIC, but assembler routines would work farily
well. (they did as a matter of fact).  Writes work just the
opposite.  You stuff data into the buffer, then command
the controller to write from the buffer to the disk.

I can't remember much more off the top of my head, but
feel free to refer any questions to me.


Pat McGee, jpm@lanl.arpa, MS: P-370, P.O. Box 1663, Los Alamos, NM 87545
Los Alamos National Labs.  505-665-0686 or FTS 855-0686