400 PPI Serial Mouse and Northgate Computers

• Microsoft Mouse Driver for MS-DOS, versions 6.x, 7.x, and 8.x
• Microsoft Serial-PS/2 Mouse, version 1.0

SYMPTOMS

When you attempt to install the 400 ppi PS/2/serial Microsoft Mouse on the 9-pin serial port of some Northgate computers, the mouse may not install.

CAUSE

When the 400 ppi Microsoft Serial-PS/2 Mouse is installed on the 9-pin serial port as a serial mouse, it uses pins 2, 3, 4, 5, and 7 to communicate with the serial port.

The other pins in the 9-pin connector are used when the PS/2 adapter is connected to the mouse. Pin 8 of the built-in serial port, when set to a logic zero, is 1 to 2 volts higher than the voltage that would be present on an IBM compatible serial port. When a logic 1 is present on pin 8 and the mouse is connected to a 9-pin serial port, the mouse cannot reset. This prevents the mouse from installing.

WORKAROUND

To work around this problem, do either of the following:

• Contact Northgate technical services. They have found the cause of the problem and can work with you to make the necessary corrections to the motherboard. Northgate says this problem (which occurs on 80386 and 80286 computers) is corrected.
• Use a 9- to 25-pin serial adapter to eliminate the signal from pin 8. To do this, you need to purchase the adapter from a local electronics store. This adapter has a 9-pin female connector on one end and a 25-pin male connector on the other end. Once you have the adapter, perform the following steps:

  1. Attach the adapter you purchased to the built-in serial port of

        your computer.
  

  2. Attach the mouse to the 25- to 9-pin serial adapter that was

        supplied with your mouse.
  

  3. Attach this adapter to the 9- to 25-pin adapter that you have

        already attached to your computer.
  

MORE INFORMATION

For more information, contact Northgate.

The Northgate product included here is manufactured by a vendor independent of Microsoft; we make no warranty, implied or otherwise, regarding this product's performance or reliability.