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Hardware-Queued Primitive Command Interface

IP.com Disclosure Number: IPCOM000042375D
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 1 page(s) / 13K

Publishing Venue

IBM

Related People

Buesing, DA: AUTHOR [+2]

Abstract

A microprocessor-based adapter for the attachment of flexible files has low speed operations, such as seeks or head loads, driven directly by the microprocessor and high speed operations involved in moving data between the system and file implemented in hardware. To reduce the amount of hardware for the high speed operations, the interface between the high speed hardware and the microprocessor is implemented using a primitive command approach. Primitive commands are basic building blocks of operations which may be chained together by software to implement any desired system level command. An example of a multirecord read command implementation is shown in Fig. 1. This particular example uses two primitive commands per record.

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Hardware-Queued Primitive Command Interface

A microprocessor-based adapter for the attachment of flexible files has low speed operations, such as seeks or head loads, driven directly by the microprocessor and high speed operations involved in moving data between the system and file implemented in hardware. To reduce the amount of hardware for the high speed operations, the interface between the high speed hardware and the microprocessor is implemented using a primitive command approach. Primitive commands are basic building blocks of operations which may be chained together by software to implement any desired system level command. An example of a multirecord read command implementation is shown in Fig. 1. This particular example uses two primitive commands per record. At the point of completion of one primitive command and the start of the next, it is desired that software intervention not be required since this would require a fast realtime response by the microcode. In order to maintain hardware-controlled continuity between commands, the adapter contains an innovation which is the use of two- position queues for command and status at the primitive command interface. Fig. 2 illustrates the use of the queues for chained primitive commands. Use of the queues is as follows: 1. At the start of a system level command, Position 1 of the command queue is loaded with the first primitive command and the hardware is started. 2. The hardware moves the primitive command from Position 1 to Position 2 of the command queue and executes the primitive command from Position 2. Status, as required, is accumulated in Position 1 of the status queue.
3. Any time during the execution of the primitive command the microprocessor may load the next primitive command into Position 1 of the command queue. 4. Upon completion of the primitive command, the...