Browse Prior Art Database

Invalid Address Correction

IP.com Disclosure Number: IPCOM000082031D
Original Publication Date: 1974-Sep-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Cianciosi, M: AUTHOR

Abstract

A method for adjusting invalid storage addresses under program control utilizes the error checking hardware of a computer system having incremental storage sizes. A system program supports means to alter addresses and data from a keyboard, as well as displaying the same on a cathode-ray tube (CRT).

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Invalid Address Correction

A method for adjusting invalid storage addresses under program control utilizes the error checking hardware of a computer system having incremental storage sizes. A system program supports means to alter addresses and data from a keyboard, as well as displaying the same on a cathode-ray tube (CRT).

Since storage size is transparent to the programming, it is necessary to accommodate a computer having variable-storage sizes with a unique program module that is customized to each of the different storage size combinations. This module would then have to be installed in the system at the time of manufacture, or in the field whenever there is a storage size change. This implies that a number of program modules have to be maintained, so that the different storage combinations can be adequately displayed when using an ALTER/DISPLAY feature.

Whenever storage is accessed by a machine instruction, a test is made by error checking circuitry on the address being used in accordance with a wire jumper on the CPU circuit board; i.e., if the circuit board is wired with a jumper for 4K of storage and the storage address is greater than 4K, an invalid storage address is detected by the error checking circuitry.

An invalid storage address causes a machine check interrupt to be invoked. In effect, the control circuitry switches from the main level Instruction Address Register (IAR) to the machine check level IAR, wherein machine instructions begin executing. The machine che...