[comp.sys.ibm.pc.hardware] 2 Game Ports, how's it done?

doerschu@rex.cs.tulane.edu (Dave Doerschuk) (05/22/91)

A friend of mine is setting up a joystick on his PC for his kids.  He
asked me to make the purchase and install it, and I have become confused
over the availability of 2 joysticks on a single PC.  Some folks do this
with a Y adapter cable; this clearly does not differentiate between
the two joysticks.  Some multi-IO boards come thru with 2 game ports, and
I was wondering if they had two separate ports, or one port with two
connectors on it.  Does any game actually require two joysticks, or can
a single joystick be exchanged between the players?

Lastly, is there more than one "standard" address to set a game port to?
I believe that no interupt line is ever used by the game port, if this is
wrong, would someone please correct me?

Thank you for your time.

Dave Doerschuk
doerschu@rex.cs.tulane.edu

jayh@ms.uky.edu (Jay Hofacker) (05/22/91)

   One 15 pin game port contains all the signals for 2 joysticks (4 positions
and 4 switches), so the Y adapters actually pass the signals straight through
to the first joystick and swap them for the second joystick.  The cards that
provide two ports simply do this splitting on the card, rather than in a Y 
cable.  The game port does not use an IRQ line, but it does have a standard
port address, so you can only have one game port on a system, unless you had
a specially configured card and specially written software.

-- 
Jay Hofacker, sysop of the Audio/Visual Exchange, (606)254-1751 3/12/24 MNP 5
Mail: jayh@ms.uky.edu / uk02779@ukpr.uky.edu -- Yes, my signature is only 2 lin

wjb@cogsci.cog.jhu.edu (05/23/91)

In article <1991May22.024043.19254@ms.uky.edu> jayh@ms.uky.edu (Jay Hofacker) writes:
>
> [correct things about game ports supporting two joystick]

	I just wanted to comment that I've had problems with inexpensive
multi IO cards where I couldn't use the second joystick port.  In
particular, the buttons were stuck in either the ON or OFF state.  It
wouldn't surprise me if the cheap boards are never tested or they didn't
bother to test the second joystick since most people never use it anyway.

				Bill Bogstad