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

  1. ^ "Arpanet DBMS Uses Decsystem-10, Mass Memory". Computerworld. Vol. XI, no. 19. May 9, 1977. p. 30.
  2. ^ Elizabeth J. Feinler, ed. (October 1978). Arpanet Resources Handbook. pp. 161–162. NTIS AD-A065 421.
  3. ^ Janet Abbate. Inventing the Internet. pp. 98–99, 103–104.
  4. ^ a b Donald E. Eastlake III; Matthew Maltzman; Joanne Z. Sattley; Steven A. Zimmerman (July 31, 1979). Datacomputer and SIP Operations: Semi-Annual Technical Report, January through June 1979 (PDF) (Technical report). Computer Corporation of America Technical report CCA-79-22.
  5. ^ Richard Winter; Jeffrey Hill; Warren Greiff (December 1973). Further Datalanguage Design Concepts. IETF. doi:10.17487/RFC0610. RFC 610.
  6. ^ a b Thomas Marill; Dale Stern (May 19–22, 1975). "The datacomputer—A network data utility". AFIPS '75 Proceedings, National Computer Conference. Anaheim, California. pp. 389–395. doi:10.1145/1499949.1500025.

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