Browse Prior Art Database

Personal Computer Keyboard Port Multi-Device Adapter

IP.com Disclosure Number: IPCOM000102241D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 2 page(s) / 61K

Publishing Venue

IBM

Related People

Martinez, PL: AUTHOR [+2]

Abstract

This article describes a device which allows for multiple-device connections into a personal computer (PC) keyboard port, thereby permitting external devices to be connected without using additional input/output (I/O) slots.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 71% of the total text.

Personal Computer Keyboard Port Multi-Device Adapter

       This article describes a device which allows for
multiple-device connections into a personal computer (PC) keyboard
port, thereby permitting external devices to be connected without
using additional input/output (I/O) slots.

      Some PCs provide for attachment of a keyboard and other devices
(i.e., mouse, scanner, magnetic card reader) through two external
device ports.  These are six-pin connectors located at the rear of
the machine.  One of the two connectors is normally attached to the
keyboard, leaving one port for additional devices.  Applications
requiring more than one device, aside from the keyboard, must
interface to the PC through an I/O card installed within the machine
which takes up a card slot.  A "smart connector" (multi-device
adapter) attaching to one of the keyboard ports houses the logic to
replicate the interface to multiple devices as shown in Fig. 1.

      The multi-device adapter of this disclosure replicates the
keyboard interface and performs the following functions:
-    Set Pseudo IDs for devices attached
-    Multiplex data from devices attached
-    Control/Arbitrate contention
-    Provide clocking synchronization for interface
-    Provide status (errors) back to keyboard interface
-    +5 volt line from system unit to devices attached

      Fig. 2 shows the hardware logic implementation in block
diagram.  A microprocessor 1 (i.e., Intel 80...