Browse Prior Art Database

Keyboard Support for Simulated Processor Power Down

IP.com Disclosure Number: IPCOM000062435D
Original Publication Date: 1986-Nov-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Krishnamurty, R: AUTHOR [+2]

Abstract

By using a three-key sequence, a coprocessor virtual terminal session can be ended in a consistent and non-conflicting way. A hardware base consisting of a high speed Reduced Instruction Set Computer (RISC) microcomputer with an IBM PC AT (Advanced Technology) compatible I/O bus is provided with compatibility with IBM PC applications by supporting the Intel 80286 coprocessor. The coprocessor option has a display support mode which allows the user to request a system display in a direct usage mode, thus disallowing primary processor intervention since the coprocessor is directly manipulating the video buffer and I/O port addresses. When working in this direct access mode, the user loses hot key capability with the primary processor virtual terminals in the terminal ring.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 79% of the total text.

Page 1 of 1

Keyboard Support for Simulated Processor Power Down

By using a three-key sequence, a coprocessor virtual terminal session can be ended in a consistent and non-conflicting way. A hardware base consisting of a high speed Reduced Instruction Set Computer (RISC) microcomputer with an IBM PC AT (Advanced Technology) compatible I/O bus is provided with compatibility with IBM PC applications by supporting the Intel 80286 coprocessor. The coprocessor option has a display support mode which allows the user to request a system display in a direct usage mode, thus disallowing primary processor intervention since the coprocessor is directly manipulating the video buffer and I/O port addresses. When working in this direct access mode, the user loses hot key capability with the primary processor virtual terminals in the terminal ring. The reason for this inconvenience is that there is no primary processor display support code to maintain the state of the video registers so as to restore the display adapter when reactivated through the terminal ring. An alternative method was required to close out the coprocessor virtual terminal session gracefully and return the user to the next virtual terminal in the terminal ring. The only devices available to aid the user with terminal resources are the display and the keyboard, but with the display dedicated to the coprocessor, the only alternative in direct display access mode is the keyborad. The keyboard used is a superset of the PC AT...