Browse Prior Art Database

Computer Access Method

IP.com Disclosure Number: IPCOM000076538D
Original Publication Date: 1972-Mar-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 5 page(s) / 43K

Publishing Venue

IBM

Related People

Meyer, JW: AUTHOR

Abstract

There is described a program which is a table driven computer computer access method, which employs binary synchronous communications. The program facilitates binary synchronous communication between computers with like or unlike operating systems. It also enables ready expansion to include communications between differing computers. Thus, given a hardware connection between differing computers over some common-carrier facility, the means of communicating between the computers through the disclosed computer access method is determined primarily through a definition of line protocol encoded within the computer access method and adhered to by the operating systems on the communicating computers.

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Computer Access Method

There is described a program which is a table driven computer computer access method, which employs binary synchronous communications. The program facilitates binary synchronous communication between computers with like or unlike operating systems. It also enables ready expansion to include communications between differing computers. Thus, given a hardware connection between differing computers over some common-carrier facility, the means of communicating between the computers through the disclosed computer access method is determined primarily through a definition of line protocol encoded within the computer access method and adhered to by the operating systems on the communicating computers. The line protocol is determined by two factors, viz:
1) The channel programs on the communicating computers are

defined such that synchronization is maintained, i.e., when

one computer is writing, the other has to be reading.
2) A set of control characters is defined such that when any

particular one of these control characters is received,

communication synchronization and continuity is maintained

through software interpretation of the character-bit

configuration or the interrupt that it generates.

This access method includes a table consisting of a complete set of channel command words, which may be used in binary synchronous communication. Each tabled channel command word contains the command code (Dial, Read, Write, etc.) and flags (command chaining, data chaining, etc.,). A particular line protocol is defined through inclusion into the access method of an index to the table of channel command words. When referenced, the index dictates the method of building channel programs, using the tabled channel command words in a prescribed order. The final result is a channel program which will adhere to a particular definition of line protocol.

All indices are similar in organization, i.e., each index is subdivided in the same manner to include portions, which dictate the method of building channel programs which will dial a computer, read data, write data, etc. It is these subdivisions of the indices that uniquely define the protocol being used. Each subdivision contains references to the channel command word table to enable the gathering of one or more entries, not necessarily contiguous, and adding to them the data address and byte count as determined by the index, and finally grouping of all the referenced entries into an appropriate channel program. Therefore, the channel program which, for example, reads data for any particular line protocol may be uniquely determined through the read subdivision of its index, but may differ appreciably from the corresponding read index subdivision and channel program for any other line protocol. However, the end results are equivalent, i.e., data is read into the appropriate area and communication synchronization and continuity is maintained.

The access method contains four entry poi...