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Some Brief Preliminary Notes on the Augmentation Research Center Clock (RFC0034)

IP.com Disclosure Number: IPCOM000003531D
Original Publication Date: 1970-Feb-26
Included in the Prior Art Database: 2000-Sep-13
Document File: 1 page(s) / 2K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

W.K. English: AUTHOR

Abstract

The ARC clock system provides a time reference that is written into the core memory of the XDS 940 Computer. There are two types of time information available--absolute and relative.

This text was extracted from a ASCII document.
This is the abbreviated version, containing approximately 100% of the total text.

Network Working Group Bill English SRI/ARC

Request for Comments No. 34 26 February 1970

SOME BRIEF PRELIMINARY NOTES ON THE ARC CLOCK

The ARC clock system provides a time reference that is written into the

core memory of the XDS 940 Computer. There are two types of time

information available--absolute and relative.

The absolute time is written into two adjacent words of core with the

following format:

First word --

Bits 0 thru 7 contain the month code in straight binary with a

range of 1 to 12

Bits 8 thru 15 contain the day code in straight binary with a

range of 1 to 31

Bits 16 thru 23 contain the year code in straight binary with

range of 0 to 99

Second word --

Bits 00 thru 7 contain the hour code written in straight binary

with a range of 0 to 23

Bits 8 thru 15 contain the minute code written in straight binary

with a range of 0 to 60

Bits 16 thru 23 contain the second code written in straight binary

with range ofr 0 to 60

These 2 words are written once each second. It is anticipated that the

accuracy of the initial setting will be on the order of 1 second, as

referred to WWV, and that the oscillator drift rate will not account for

an accumlated error of more than 1 second every 250 days. The

oscillator and clock are provided with standby power in order to

maintain the accuracy of the system. Because of variable delays in time

required to obtain access to the 940 core memory, it is anticipated that

the short-term accuracy will be on the order of 10 to 20 microseconds.

The relative time, which is written into one word of core memory, is

simply the contents of a 24 bit binary accumulator. The rate at which

the accumulator is updated can be chosen to be either once very 100

micro seconds or once every millisecond. In either case the core

location is written each time the accumulator is updated. As above the

short-term accuracy will be about 10 to 20 microseconds and the long-

term accuracy will be the equivalent of one second every 250 days.

[ This RFC was put into machine readable form for entry ]

[ into the online RFC archives by Katsunori Tanaka 1/98 ]