Datacomputer
The Datacomputer was an ARPANET-connected database system supported by the Computer Corporation of America in Cambridge, Massachusetts. It was intended as a computing utility sharing resources among multiple ARPA projects, in particular in seismology and climatology. It operated from August 1973[1] until 1980.[citation needed]
It was hosted on a DEC PDP-10 running the TENEX operating system (ARPANET host CCA-TENEX, address 31)[2] and was designed to support 3 trillion bits of storage (375 GB). Besides storage, the Datacomputer also offered data conversion utilities which supported the multiple data formats used at the time.[3]
The largest user of the Datacomputer was ARPA's Seismic Data Analysis Center (SDAC) (Alexandria, Virginia), which monitored underground nuclear tests.[4]
The Datacomputer manipulated data using a custom Datalanguage.[5] A sample retrieval request:[6]
OPEN RESULTLIST ;
OPEN WEATHER ;
FOR WEATHER.STATION WITH REGION EQ 'MASSACHUSETTS'
FOR RESULTLIST.RESULT, OBSERVATION WITH TEMPERATURE.MAX GT '300' /* DEGREES KELVIN */
RESULT.CITY = STATION.CITY ;
RESULT.DATE = OBSERVATION.DATE ;
RESULT.TEMPERATURE = OBSERVATION.TEMPERATURE ;
END ;
END;
The Datacomputer hardware had a three-level store: primary core, secondary hard disk, and tertiary mass storage. At the time, disk cost about $20/megabit, while mass stores, typically robotic magnetic tape systems, cost about $1/megabit. The service started in 1973 with disk storage only; tertiary storage using Ampex's Terabit Memory System (TMS) hardware, based on videotape technology, was to come on line in 1975.[6] In 1979, TMS's capacity was 175 billion bits (22 GB), and the total data stored was over 500 billion bits (62 GB)[4]
Notes
[edit]- ^ "Arpanet DBMS Uses Decsystem-10, Mass Memory", Computerworld, May 9th 1977
- ^ Elizabeth J. Feinler, ed., Arpanet Resources Handbook, October 1978, NTIS AD-A065 421, p. 161-162
- ^ Janet Abbate, Inventing the Internet, p. 98-99, 103-104
- ^ a b Donald E. Eastlake III, Matthew Maltzman, Joanne Z. Sattley, Steven A. Zimmerman, "Datacomputer and SIP Operations: Semi-Annual Technical Report", Computer Corporation of America Technical report CCA-79-22, July 31, 1979 at DTIC
- ^ Richard Winter, Jeffrey Hill, Warren Greiff, "Further Datalanguage Design Concepts", Network Working Group RFC 610, December 1973, full text
- ^ a b Thomas Marill, Dale Stern, "The datacomputer—A network data utility", AFIPS '75 Proceedings, National Computer Conference, May 19-22, 1975, Anaheim, California, doi:10.1145/1499949.1500025, p. 389-395