Q46369: InPort/Bus Mouse Comparison and Overview

Article: Q46369
Product(s): See article
Version(s): 1.00
Operating System(s): OS/2
Keyword(s): ENDUSER | SR# G890626-21385 | mspl13_basic
Last Modified: 31-AUG-1989

Question:

Could you clarify the difference between the Microsoft Bus Mouse and
the InPort Mouse?

Response:

The Microsoft InPort device interface is a low-cost graphic device
interface consisting of a 40-pin custom LSI IC and a compact 9-pin
circular connector, which supports a variety of graphic input devices,
especially mice.

The following is a comparison between old Bus Mouse and new InPort
Mouse:

1. The InPort Mouse uses a custom Microsoft designed 40-pin LSI
   interface chip manufactured by OKI Inc. of Japan.

   The Bus Mouse uses a generic Intel 8255A parallel interface chip.

2. The InPort Mouse allows the CPU interrupt rate to be programmable
   from 0 (no interrupt) to 200 Hz.

    The Bus Mouse CPU interrupt rate is fixed at 30 Hz.

3. The InPort Mouse interrupts the CPU only when the mouse position
   or button status has changed.

    The Bus Mouse interrupts the CPU constantly regardless of mouse
    (in)activity.

4. The InPort Mouse requires only two I/O operations to read the mouse
   XY position.

   The Bus Mouse requires four I/O operations to read mouse XY
   position.

5. The InPort Mouse uses the compact Hosiden 9-pin circular connector.

   The Bus Mouse uses the bulky DB-9 connector.

When used stand-alone with an IBM XT/AT PC, both mice use an interface
board that plugs into the standard IBM XT/AT bus. In addition, since
the InPort custom IC is essentially an enhanced, single-chip version
of the Microsoft Bus Mouse interface board, other manufacturers can
easily add the InPort interface to their PC plug-in cards. The
following are examples:

1. The Microsoft MACH 10 enhancement board

2. Renaissance GRX graphics add-in boards

3. Selected Verticom graphics controllers/adapters come with an InPort
   interface.

The InPort Mouse can also connect to an RS-232 serial port, or the
IBM PS/2 mouse port through an external adapter box.

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