From 4bfd864f10b68b71482b35c818559068ef8d5797 Mon Sep 17 00:00:00 2001 From: Thomas Voss Date: Wed, 27 Nov 2024 20:54:24 +0100 Subject: doc: Add RFC documents --- doc/rfc/rfc34.txt | 115 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 115 insertions(+) create mode 100644 doc/rfc/rfc34.txt (limited to 'doc/rfc/rfc34.txt') diff --git a/doc/rfc/rfc34.txt b/doc/rfc/rfc34.txt new file mode 100644 index 0000000..5f3dacc --- /dev/null +++ b/doc/rfc/rfc34.txt @@ -0,0 +1,115 @@ + + + + + + +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 + + + + [Page 1] + +RFC 34 Prelimary Notes on the ARC Clock February 1970 + + +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 ] + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + [Page 2] + -- cgit v1.2.3