Re: Mouse hookup

[dempson@swell.actrix.gen.nz (David Empson)]

In article <1993Aug21.194824.21801@pro-lep.cts.com> robertf@pro-lep.cts.com (Robert Fletcher) writes:
> So I have been told that a mouse is hooked up to the game port of my
> machine, but are there other ways of doing it?

Only on a IIc.  The IIc "game port" is specially designed to accept
either a mouse or a joystick.

On a II+ or IIe, you need an interface card to connect a mouse.

On the IIgs, the mouse daisy-chains from the keyboard (via Apple
Desktop Bus).

> My GEOs program had me put a special card into my mother board if I
> did not have a mouse. 

GEOS requires timing interrupts, which are normally provided by the
mouse card (along with mouse support).  The special card with GEOS
provides the timing interrupts and nothing else.

> So will some of my program, that use the mouse, need that mouse to be
> in a special place?

Not if you've written your programs properly.  You should be scanning
the slots to locate the mouse, not assuming it is in a particular slot.

For the IIgs, the mouse has always been in slot 4.  On the IIc, it is
either in slot 4 or slot 7, depending on the ROM revision.  On a IIe,
it could potentially be in any slot.

You should always scan the slots to find the mouse.  Look for the
following bytes:

$Cn05 = $38
$Cn07 = $18
$Cn0B = $01
$Cn0C = $20   (the low nibble may be nonzero for third-party mice)

n is the slot number.