Browse Prior Art Database

Time-of-Day Synchronization for Multiple Data Processors

IP.com Disclosure Number: IPCOM000099480D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-14
Document File: 3 page(s) / 75K

Publishing Venue

IBM

Related People

Fratezi, A: AUTHOR [+3]

Abstract

Multiple data processing systems can be synchronized for time-of-day (TOD) by providing compatible RS232 voltage levels, a "Sync Port" on the communications subsystems controller of each system, and a program running under customer information control system (CICS) to enable the sync ports and wait for the data set ready (DSR) active signals and copy the processor time.

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This is the abbreviated version, containing approximately 75% of the total text.

Time-of-Day Synchronization for Multiple Data Processors

       Multiple data processing systems can be synchronized for
time-of-day (TOD) by providing compatible RS232 voltage levels, a
"Sync Port" on the communications subsystems controller of each
system, and a program running under customer information control
system (CICS) to enable the sync ports and wait for the data set
ready (DSR) active signals and copy the processor time.

      The converter circuit in Fig. 1 provides required voltage
levels for producing RS232 output time signals from the master clock
to the several connected processors.  Each output comprises a DSR
line and ground.  Fig. 2 shows a schematic diagram of a pair of
processors 1 each connected through an integrated communications
adapter 2 and having respective transaction terminals 3 attached
through multiplexers 4.  TOD signals occur typically at the time
XX:57:54 for eight seconds.  When the DSR goes active, the CICS
portion of the program copies the time.  A delta value is created by
comparing the master clock time with the system TOD.  Since the hour
value (XX) is not known, the delta value is created by assuming the
synchronization point is the closest value to the processor's current
TOD.  A plus or minus delta value can now be added to the processor
system TOD whenever the time is sent to its connected terminals.
Accuracy is improved by including known times for processing the
interrupt, or fetching the system TOD, or averag...