Browse Prior Art Database

Shift-Print Screen for Personal Computer Local Area Network Redirectors

IP.com Disclosure Number: IPCOM000105757D
Original Publication Date: 1993-Sep-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Christopher, KW: AUTHOR [+2]

Abstract

Described is a method to provide personal computer (PC) Shift-Print screen redirector support for local area network (LAN) functions. The method implements the hooking of two interrupts.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 59% of the total text.

Shift-Print Screen for Personal Computer Local Area Network Redirectors

      Described is a method to provide personal computer (PC)
Shift-Print screen redirector support for local area network (LAN)
functions.  The method implements the hooking of two interrupts.

      In prior art, PC-Network and PC-LAN prohibited a Shift-Print
screen operation to redirect devices because redirection would cause
illegal PC-disk operating system (PC-DOS) re-entrancy.  The concept
described herein enables the Shift-Print screen function to operate
on PC-LAN redirectors.

      Typically, in order for redirection support to allow
Shift-Print screen operations to redirect terminal devices, it must
call PC-DOS.  Since the Shift-Print screen key combination can occur
at any time, an application may have called PC-DOS; however, re-entry
for this operation is not always supported by PC-DOS.  The concept
described herein provides a means of removing this restriction by
providing two interrupt-hooking routines.

      The first routine - PC-DOS INT 21 hook routine pre-processes
and post-processes so that each call to PC-DOS sets a flag called
Shift-Print screen inhibit (SPSI) to indicate that PC-DOS is
currently executing.  When PC-DOS completes its processing and
returns to this interrupt hook, the SPSI flag is reset and the
Shift-Print screen count is checked.  If the count is not zero, then
INT 05 is executed and the count is decremented.  When the count is
zero, the rou...