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From: lauch@cpsc.ucalgary.ca (Christopher Lau)
Newsgroups: comp.sys.apple
Subject: Re: Manuals, Mice, and the PC Transporter
Summary: Apple Mouse??
Keywords: Mouse
Message-ID: <1520@cs-spool.calgary.UUCP>
Date: 22 Jul 89 03:16:37 GMT
References: <2328@uwovax.uwo.ca>
Sender: news@calgary.UUCP
Reply-To: lauch@vaxa.UUCP (Christopher Lau)
Organization: U. of Calgary, Calgary, Alberta, Canada
Lines: 41

Can anyone out there describe to me the circuit used in an Apple mouse //e|//c
I've got several generic-type 2 button mice that I'd like to modify for use
on my Apple..

These mice contain the standard opto-mechanical mechanism (2 opto sensors
nearly 180 degrees apart for each direction) and they use an LM339 quad
comparator to generate the signals..  I've tested all of them (not connected
to the computer, just power to the connector..) and they give the following:

 Voltage input : 4.94 VDC @ 150 mA (max)
 Opto-sensor outputs :  Low ("0") = 0.76 VDC
		        High ("1") = 4.87 VDC
 Button outputs	: Off = 0.00 VDC
		  On = 4.94 VDC

I've wired several of them to the appropriate connector and plugged them into
the computer.  The buttons (I've wired both together so that they both act
as a single switch) are the only things that work!!! The mouse select is
active (pin 1 on the 9 pin DIN connector) but it seems that the output lines
from the comparator are pulled low..  I know that it isn't the fault of the
computer, as the results were the same both before and after I got the
motherboard replaced (blown IWM chip from accidentally pulling out the ext.
drive connector while power on).   I've got the //c Technical Ref Manual
and in chapter 11, it explains a bit about the mouse, but I can't make sense
of the voltage vs. current graphs that appear there...  it SEEMS to me that
a 0V,0mA is a "1" to the computer, and then a voltage between 2&3V (I'm
quoting from memory, so the ranges aren't exact) is a "0" and anything
between 4.5 and 5V is again a "1"...  Can anyone (especially someone at Apple)
tell me what this means?? does it mean that I have to change the resistors
on the comparator to give 2V instead of 0.76V??   HELP!!  I'm desparate to
get these creatures working..

Please post or email replies..

Thanks in advance
Chris

Email-> lauch%vaxa@cpsc.ucalgary.ca (Machine I'm posting from)
	CYLau@UNCAMULT.BITNET       (Preferred)

Disclaimer->  I didn't say any of this... the computer did!!