Browse Prior Art Database

Multiple Timer Service

IP.com Disclosure Number: IPCOM000085440D
Original Publication Date: 1976-Apr-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Callahan, RW: AUTHOR [+2]

Abstract

In data processing systems employing variably microprogrammable central processors and input/output support processors (the latter viewable as intelligent channels providing services highly transparent to task programs transferred between the central and support processors), a service which may be profitably performed by the support processor is that of timing input/output transfer processes relative to the storage system which is commonly accessible to both processors.

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Multiple Timer Service

In data processing systems employing variably microprogrammable central processors and input/output support processors (the latter viewable as intelligent channels providing services highly transparent to task programs transferred between the central and support processors), a service which may be profitably performed by the support processor is that of timing input/output transfer processes relative to the storage system which is commonly accessible to both processors.

For high-performance peripheral (I/O) interfaces it is undesirable to perform the timing function at a high level of system programming, and yet it is equally undesirable to provide discrete time-out hardware per I/O port or other interface unit. The presently described system, which employs a single timer microprogram in a time-divided microprocess to perform multiple timer functions concurrently relative to multiple I/O interfaces or ports, represents a possible efficient solution to this problem.

The timer instruction stream (Fig. 1) represents an "ancillary" timer microprogram, which is executed in time division multiplex with other more directly productive microprograms of the support processing system. This stream examines multiple timer value count parameters held in a dedicated area of system storage (Fig. 1) which have appropriate validity status (V). Upon detecting an elapsed time-out end (zero timer value) the timer instruction stream instigates signaling relative...