Browse Prior Art Database

Core Storage Lockout Circuit

IP.com Disclosure Number: IPCOM000097721D
Original Publication Date: 1961-May-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Annunziata, EJ: AUTHOR [+3]

Abstract

The addressable core storage lockout circuit selectively prevents storage in a selected area of a memory. This particular core storage memory is used by either of two portions of a data processing system, the Central Processing Unit (CPU) or the Input-Output Units (I/O).

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 2

Core Storage Lockout Circuit

The addressable core storage lockout circuit selectively prevents storage in a selected area of a memory. This particular core storage memory is used by either of two portions of a data processing system, the Central Processing Unit (CPU) or the Input-Output Units (I/O).

If, for example, it is desired to protect an area of memory, e. g., Area A, from a CPU address, up levels are applied to both inputs of AND 20, the Set Protect Mode (SPM) having been previously energized. Trigger 21 is thus energized and partially conditions AND
22. While the CPU is using the memory, an up level is applied to the CPU time input of AND 22. Its coincidence condition satisfied, AND 22 applies an input to OR 26 which in turn partially conditions AND
27.

Should the decoder 28 now receive an Area A memory instruction from CPU, an up level is applied to input 32 of AND 27, satisfying its coincidence condition and causing it to produce a Trap signal. This output blocks the Area A instruction and causes it to be stored in another area of memory. An indication of this storage is sent to the operator's console. A similar sequence occurs if it is desired to lock out Area A of memory against an I/O store instruction.

1

Page 2 of 2

2

[This page contains 2 pictures or other non-text objects]