Re: Old IBM mouse on //e?

[et472@FreeNet.Carleton.CA (Michael Black)]

Simon Williams (DON'Temail@luddite.ca) writes:
> I keep seeing non-Apple mice at thrift stores that seem to have the
> same 9 pin connector as the AppleMice... I know that the extra button(s)
> won't work no matter what, but can the mice function at all on a //e or
> //c???
> 
> Additionally, why didn't I just spend the $1.75 that would have answered
> my question already???
> 
> SW

I suspect you didn't just spend the money because if you were concerned that
you'd do damage if you just plugged it in without checking.

Just because a connector is the same doesn't mean it uses the same pinout
or internal circuitry.

However, since Joel has explained the details of the Apple II mouse,
what you might be able to do is use the mouse.

One time after getting my Mac Plus in late 1993, I came across some IBM-type
mice for a dollar each at a garage sale, and I bought some out of curiosity.
I knew I couldn't plug them into the Mac.  But since I'd had my Mac Plus
mouse open, I think I'd even traced the circuitry at that point, I realized
that if I bypassed most of the circuitry in the IBM mouse, and wired 
correctly to the connector, I'd get a Mac Plus mouse.  I tried it and
it worked fine, though I went back to the Mac mouse because I was
used to it.

If you know nothing of electronics this won't mean anything.

There are a two slotted wheels inside that rotate with the movement of
the mouse ball.  On each wheel there are a pair of optocouplers in the 
the Mac (and apparently Apple II) mouse.  In the Mac Plus mouse,
the outputs of these four optocouplers each go through a stage of buffering
(from memory, I thought it was an LM339 quad comparator, or maybe an LM324
quad op-amp), and then to the connector.  The button, a simple switch,
goes to the connector.  I thought it was buffered too, but that couldn't
be the case if it used one of the above ICs.  And voltage from the Mac
goes to power the optocouplers and the buffers.

In the IBM mouse I modified, I just wired the connector to the outputs
of the optocouplers, not worrying about buffering it.  The same with the
switch.  Got it powered up, and it worked.  I couldn't tell any difference
in operation other than the different physical shape.

So with a bit of soldering anyone can have a cheap Apple mouse.

   Michael