Xylogics 753 + CDC Sabre 9720-850

[Steve Jay]

In v7n215, Richard Robison (rr%chmsr at gatech.edu) asks for switch settings
for a Xylogics 753 + CDC Sabre 9720-850.  We are running exactly this
configuration on our 3/280 server with OS 3.3.

The Xylogics 753 is set to the "Factory Configuration" except the Base
Address is at eed0.

The CDC Sabre 9720-850 "I/O Board" switches (see page 3-41 of the
Installation and Checkout manual that came with it [CDC pub #83325710,
rev. C]) are:

	   switch        setting 		Description
	1A/1D, 1B/1D	 1A & 1D	Index/Sector pulses on A cable only
	RDY/POK		   RDY		Normal I/O ready status
	T2/T1		   T1		Enable Ext. Cyl. Addr. via Tag 1
	E/O		   E		SMD-E mode
 	XA/N		   XA		Extended Cylinder Addresses
	R/L		   L		Local power on

The "Control Board" switches (see page 3-46 of the manual) are:

	   switch        setting 		Description
	logical address   ---		[ whatever you want, probably 0 ]
	Sector switches  (see below)	# bytes in sector
	.8/1.6		   1.6		Sector Clock Freq. 1.6 MHZ
	B/C		    B		Byte frequency sector clock
	WP/N		    N		not write protected
	RUNT jumper	 disconnected	Runt sector pulses may appear
	SWP1 jumper	  connected	Disable sweep only on seeks
	SWPD jumper	  connected	Disable sweep cycles

Switches & jumpers not mentioned are "don't care".

For the Sector switches, we used 68 sectors per track, which works out to
604 bytes per sector according to the chart on page 3-77 of the manual
(Byte clock round-down method).  The switches are therefore O O C O O C O
C C 0 C C C C, going from bit 0 to bit 13, with "O" meaning open, and "C"
meaning closed.

When formatting, we told it 1379 cylinders, 2 spare cylinders, 15 tracks,
67 sectors, 604 bytes/sec.  Note that with the drive set for 68
sectors/track, but formatting for 67, there's room for one "slip" sector
per track.

We use the Xylogics supplied xl driver for our 3.3 system.  We are told,
but haven't yet tried, that the standard xd driver from Sun in OS 4 will
handle this controller/drive configuration.  Jim Budler (jim at eda.com) in
v7n45, gives his experiences in using the same hardware under OS 4.  My
thanks to him, as that's where I got the confirmation about what sector
size to use.

Contact me if you need more information.

Steve Jay                       domain: shj at ultra.com
Ultra Network Technologies	Internet: ultra!shj at ames.arc.nasa.gov
101 Daggett Drive               uucp: ...ames!ultra!shj
San Jose, CA 95134		
408-922-0100