Browse Prior Art Database

Personal Computer Remote Operation Interface

IP.com Disclosure Number: IPCOM000102815D
Original Publication Date: 1990-Feb-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 50K

Publishing Venue

IBM

Related People

Rieth, PF: AUTHOR

Abstract

Disclosed is a method of low level control of the user interface of a personal computer for the purpose of controlling operations from a remote computing system.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 73% of the total text.

Personal Computer Remote Operation Interface

      Disclosed is a method of low level control of the user
interface of a personal computer for the purpose of controlling
operations from a remote computing system.

      Most applications that support remote operations to a personal
computer do so by inserting the desired keystrokes into a keystroke
buffer maintained by the Disk Operating System (DOS).  While this
method is adequate in some cases, it does not work for all
applications.  In particular, a class of applications called 'hot key
programs', which bypass the DOS keystroke buffer and directly monitor
keystroke activity, cannot be completely controlled by this old
method.

      The Basic Input Output System (BIOS) keyboard handler, or the
current owner of the keyboard interrupt (i.e., the hot key program to
be controlled), receives keystrokes in the form of scan codes from
the keyboard hardware by reading them from the I/O port at
hexadecimal 60 (x'60').  The machine language operand code (opcode)
to implement this operation is an x'E4' and the associated operand is
x'60'. By changing the x'E4' opcode (I/O port read) to an x'CD'
opcode (call software interrupt handler), a program can be made to
gain control of the processor (at software interrupt x'60') whenever
the keyboard port is to be read.  A keystroke can then be inserted or
altered by placing the equivalent scan code in the processor's
accumulator register (AX reg) before returning control to...