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Free-Running Functions in a Serial-Accessed Processing Unit

IP.com Disclosure Number: IPCOM000060491D
Original Publication Date: 1986-Apr-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Laurent, B: AUTHOR [+2]

Abstract

A Service Processor is linked to a Processing Unit through the serial path provided by the LSSD feature; i.e., all latches are doubles and linked together according to the Level Scan Sensitive Design technique. The major problem with such an implementation is the need for some parts of the logic to run freely without interruption by the serial LSSD access (Fig. 1). The partitioning optimization may lead to having in the same LSSD entity a freezable logic and some free-running facilities. A problem is to control separately the different logic parts by the serial access in order to allow, for instance, a timer to run or a memory to be refreshed in spite of a serial observation in the LSSD entity. This is solved by a specific serial control dedicated to each function. In Fig.

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Free-Running Functions in a Serial-Accessed Processing Unit

A Service Processor is linked to a Processing Unit through the serial path provided by the LSSD feature; i.e., all latches are doubles and linked together according to the Level Scan Sensitive Design technique. The major problem with such an implementation is the need for some parts of the logic to run freely without interruption by the serial LSSD access (Fig. 1). The partitioning optimization may lead to having in the same LSSD entity a freezable logic and some free-running facilities. A problem is to control separately the different logic parts by the serial access in order to allow, for instance, a timer to run or a memory to be refreshed in spite of a serial observation in the LSSD entity. This is solved by a specific serial control dedicated to each function. In Fig. 2, Control 1 signal is the least inhibiting (and powerful) serial control code. Control 4 signal is the most inhibiting (and powerful) serial control code and blocks the more vital function such as the Storage Refresh and the Ecipt latches which are LSSD latches connected to the output driver to capture the output value. To minimize the LSSD entity input/output count, it has been chosen to have just one serial in/out couple for all the facilities. Depending upon the different phase of the start- up, the manufacturing test or the function run, flexibility is thus given to progressively control or/and observe through the serial LSSD acce...