Free-Running Functions in a Serial-Accessed Processing Unit
Original Publication Date: 1986-Apr-01
Included in the Prior Art Database: 2005-Mar-08
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.