Browse Prior Art Database

Remote Alter and Display Mechanism for System Storage

IP.com Disclosure Number: IPCOM000045189D
Original Publication Date: 1983-Feb-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Crandall, DR: AUTHOR

Abstract

A mechanism is described whereby a human operator sitting at a key board/display unit can display or alter one or more of the storage locations in a main storage unit associated with a data processor to which the keyboard/display unit is attached. This can be accomplished while the processor is running a user program and without in any way disturbing the processor.

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Remote Alter and Display Mechanism for System Storage

A mechanism is described whereby a human operator sitting at a key board/display unit can display or alter one or more of the storage locations in a main storage unit associated with a data processor to which the keyboard/display unit is attached. This can be accomplished while the processor is running a user program and without in any way disturbing the processor.

As indicated in the drawing, the keyboard/display unit is connected to the data processor by way of an I/O controller. The processor and its I/O channel are such that the I/O controller can at any time cycle steal data or other information into or out of the main storage unit without interrupting the program being executed by the processor. This cycle stealing capability makes possible the remote alter and display operations.

The I/O controller includes a microprocessor, a read-only storage (ROS) module and a random-access memory (RAM) module. The ROS module contains the microcode which runs the I/O controller. For the case of a keyboard/display unit, the RAM module includes, among other things, a display screen buffer for storing a complete copy of the picture appearing on the display screen of the display unit during its normal operation.

The remote alter and display function is implemented by means of an appropriate microcode routine which is included as part of the microcode in the I/O controller. In order to invoke this alter and display microcode, the operator enters a sequence of three unique key strokes on the keyboard of the keyboard/display unit. This sequence is one that would be extremely unlik...