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Programmable Burst Control for Load/Store Operations

IP.com Disclosure Number: IPCOM000120210D
Original Publication Date: 1991-Apr-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 1 page(s) / 31K

Publishing Venue

IBM

Related People

Arimilli, RK: AUTHOR [+3]

Abstract

Load/Store on the Micro Channel* is executed at the lowest priority and the processor is locked. With the load/store at the lowest priority, it is important that, once started, it execute the maximum number of cycles allowed by the Micro Channel Architecture (7.8 microseconds) and release the processor in the least amount of time.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 91% of the total text.

Programmable Burst Control for Load/Store Operations

      Load/Store on the Micro Channel* is executed at the
lowest priority and the processor is locked.  With the load/store at
the lowest priority, it is important that, once started, it execute
the maximum number of cycles allowed by the Micro Channel
Architecture (7.8 microseconds) and release the processor in the
least amount of time.

      Two bits are architected to maximize bus utilization. These
Burst Control bits are encoded as:
                             00 - Immediate
                             01 - 1.6 microseconds
                             10 - 3.2 microseconds
                             11 - 6.4 microseconds

      The load/store operation will complete if no other device
requests use of the Micro Channel ('- PREEMPT' inactive).  If '-
PREEMPT' is active, a counter is started. When the counter value
equals that of the encoded Burst Control bits, the bus is
relinquished.  Setting the Burst Control bits to a high value ensures
maximum utilization of the Micro Channel for load/stores.  Since the
majority of the load/store operations are short, it completes under a
single arbitration.  The Burst Controls were encoded in microseconds,
rather than number of cycles, to get an accurate measure of the time.

      In the future, there may be a design point for load/stores to
ex...