Message-ID: <2764@brl-tgr.ARPA>
Date: Fri, 4-May-84 17:12:22 EDT
Article-I.D.: brl-tgr.2764
Posted: Fri May  4 17:12:22 1984
Date-Received: Tue, 8-May-84 07:10:35 EDT
Organization: Ballistics Research Lab
Lines: 20


	I wanted to add a three position switch to my apple drives. One
position would write-protect the disk independent of the disk notch,
one position would write-enable independent of the disk notch and the
third position would allow the disk notch to function normally. This would
be easy to do if one side of the disk notch microswitch was grounded or tied
to +5V. 
	To my great dismay, I discovered that the disk notch microswitch
is not connected to ground or +5V. On page 146, Circuit Schematic: Disk II
Analog Board, The DOS Manual, one side of the microswitch is connected
to the pad marked W PROT and the other side is connected to WP RET.
W PROT is wired to IC B4, pin 2 which provides the microswitch status
to the digital card. WP RET is connected to the Phase 1 line.
	Does anyone know why the Phase 1 connection is made? Why isn't 
this side of the switch simply grounded or tied to +5? What would be the
consequences of breaking the Phase 1 connection?

Howard Walter
howard@brl
...!decvax!brl-bmd!howard