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Real Time Random Access Memory Assignment to Wire Images and or Microcode Patches

IP.com Disclosure Number: IPCOM000052847D
Original Publication Date: 1981-Jul-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 3 page(s) / 74K

Publishing Venue

IBM

Related People

Malkemes, CD: AUTHOR [+2]

Abstract

A microprogramming technique is described that is useful in a computer system, such as an IBM Series/l system having random-access memory (RAM) and a wire matrix printer or similar device. Potentially more bytes of RAM are made available for microcode patches and wire image loads. Storage allocations of RAM and various conditions 1-4 following commands received from the central processing unit (CPU) are illustrated in the drawing.

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Real Time Random Access Memory Assignment to Wire Images and or Microcode Patches

A microprogramming technique is described that is useful in a computer system, such as an IBM Series/l system having random-access memory (RAM) and a wire matrix printer or similar device. Potentially more bytes of RAM are made available for microcode patches and wire image loads. Storage allocations of RAM and various conditions 1-4 following commands received from the central processing unit (CPU) are illustrated in the drawing.

In a representative system, there are about 3600(+) bytes of RAM out of 4K available that are assigned to the wire image buffer area and the microcode patch area. The rest of the RAM is used for print buffer, stack area, and flags. The exact length of these areas is subject to change.

The current loadable wire image typically is about 3500 bytes long but may change in length. This leaves about 100 unused bytes of RAM which can be used for microcode patches. One hundred bytes of storage is not very much space in case a substantial patch is required. Also, the 100 bytes can be used for a longer wire image load if it is needed.

Wire image data is loaded into the lower addressed area of RAM upwardly and patch data is loaded (apparently but not actually) from the higher addressed area of RAM downwardly.

The microcode routines allocate the unused area of RAM to either wire images or patches or both. At RAM initialization time, the maximum possible length for both wire images and patches is set to the length of the unused portion of RAM (about 3600 bytes). When a wire image is loa...