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Remote Spooling Communications Subsystem or RSCS is a subsystem ("virtual machine" in VM terminology) of IBM's VM/370 operating system which accepts files transmitted to it from local or remote system and users and transmits them to destination local or remote users and systems. RSCS also transmits commands and messages among users and systems. RSCS is the software that powered the world’s largest network (or network of networks) prior to the Internet and directly influenced both internet development and user acceptance of networking between independently managed organizations. RSCS was developed by Edson Hendricks and T.C. Hartmann. Both as an IBM product and as an IBM internal network, it later became known as VNET. The network interfaces continued to be called the RSCS compatible protocols and were used to interconnect with IBM systems other than VM systems (typically MVS) and non-IBM computers. The history of this program, and its influence on IBM and the IBM user community, is described in contemporaneous accounts and interviews by Melinda Varian.〔Varian〕 Technical goals and innovations are described by Creasy 〔Creasy〕 and by Hendricks and Hartmann〔Hendricks and Hartmann〕 in seminal papers. Among academic users, the same software was employed by BITNET and related networks worldwide. ==Background== RSCS arose because people throughout IBM recognized a need to exchange files. Hendricks’s solution was CPREMOTE, which he completed by mid-1969. CPREMOTE was the first example of a “service virtual machine” and was motivated partly by the desire to prove the usefulness of that concept. In 1971, Norman L. Rasmussen,〔The father of Nicolas Rasmussen.〕 Manager of IBM’s Cambridge Scientific Center (CSC), asked Hendricks to find a way for the CSC machine to communicate with machines at IBM’s other Scientific Centers. CPREMOTE had taught Hendricks so much about how a communications facility would be used and what function was needed in such a facility, that he decided to discard it and begin again with a new design. After additional iterations, based on feedback from real users and contributed suggestions and code from around the company, Hendricks and Tim Hartmann, of the IBM Technology Data Center in Poughkeepsie, NY, produced RSCS, which went into operation within IBM in 1973. The first version of RSCS distributed outside of IBM (1975) was not a complete networking package. It included uncalled subroutines for functions such as store-and-forward that were included in the IBM internal version. The store-and-forward function was added in the VNET PRPQ,〔A PRPQ (Programming Request for Price Quotation), was an IBM administrative term for software that was available but not fully supported as an IBM product〕 first for files, and then for messages and commands. Once those capabilities were added, “the network began to grow like crazy.”〔Varian, p. 41〕 Although at first the IBM network depended on people going to their computer room and dialing a phone, it soon began to acquire leased lines. At SHARE XLVI, in February, 1976, Hendricks and Hartmann reported that the network, which was now beginning to be called VNET, spanned the continent and connected 50 systems. By SHARE 52, in March, 1979, they reported that VNET connected 239 systems, in 38 U.S. cities and 10 other countries. “VNET passed 1000 nodes in 1983 and 3000 nodes in 1989. It currently (1990s) connects somewhat more than 4000 nodes, about two-thirds of which are VM systems.” 〔Varian, p. 42〕 In comparison, by 1981 the ARPANET consisted of 213 host computers. Both ARPANET and VNET continued to grow rapidly. By 1986, IBM’s Think magazine estimated that VNET was saving the company $150,000,000 per year as the result of increased productivity. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「RSCS」の詳細全文を読む スポンサード リンク
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