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From: dowson@utecfa.UUCP (Jim Dowson)
Newsgroups: net.wanted,net.periphs
Subject: help needed with 9877 CDC drive and SMD controller
Message-ID: <1783@utecfa.UUCP>
Date: Tue, 4-Feb-86 00:50:36 EST
Article-I.D.: utecfa.1783
Posted: Tue Feb  4 00:50:36 1986
Date-Received: Tue, 4-Feb-86 05:21:16 EST
Organization: Engineering Computing Facility, University of Toronto
Lines: 48


I am trying to hook up a CDC 9877 (BK5XX) 80 Mb removable storage SMD drive
via a CDC 9090 multibus interface card to a Xenix system (3.0).

The pertinent specs for the drive are:

	1)	20,160	bytes/track
	2)	5	tracks/cylinder
	3)	823	cylinders/spindle
	4)	13,440	dibits/revolution (? allegedly)

The pertinent facts for the controller are:

	1)	512	data bytes/sector
	2)	63	bytes control information/sector

Here's the problem:

    There are formulae in the installation manual that are as follows:

	SL = 13440/RS 	(ignore remainder)
			where SL = sector length
			      RS = required number of sectors (/track)
			      13440 = total dibits/revolution

	PV = 4096 - SL
			where PV = preset value to be encoded by the DIP
				   switches

Here's how I (tried to) figure it:

	SL = 13440/35	= 384	(I want 35 sectors/track)
	PV = 4096 - 384	= 3712

However, this doesn't work, nor does +/- 1 ...

Frankly, I don't understand where the 13,440 number came from - so I even
tried using 20,160 (the number of bytes/track) ... that didn't work either.

In all cases the error code from the controller indicated "sector pulse not
found".....

Help ......

Please mail responses to:
{ihnp4,allegra,decvax,linus}!utzoo!{spectrix,utecfa}!bml!jim

Jim Dowson