Browse Prior Art Database

Isolation of Multiple Communications Functions From Each Other

IP.com Disclosure Number: IPCOM000042802D
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Bentley, AM: AUTHOR [+3]

Abstract

Multi-line communications adapter 10 shares control of the same data communications line by the mutually incompatible X.21 switched connect/disconnect protocol and SDLC/BSC (Synchronous Data Link Control/ Binary Synchronous Communication) transfer protocols. The X.21 switched connect/disconnect function is isolated into a reentrant microcode module. Commands from tasks that require connection or disconnection of the data link are routed to the X.21 module. The X.21 module 11 has the ability to modify line supervisor module 12 to cause it to route character interrupt control to the X.21 module 11 instead of to the normal SDLC/BSC protocol modules 12 and 13. This is done by the X.21 module for the X.21 data link connect/disconnect phase shown symbolically by dashed lines 14.

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Isolation of Multiple Communications Functions From Each Other

Multi-line communications adapter 10 shares control of the same data communications line by the mutually incompatible X.21 switched connect/disconnect protocol and SDLC/BSC (Synchronous Data Link Control/ Binary Synchronous Communication) transfer protocols. The X.21 switched connect/disconnect function is isolated into a reentrant microcode module. Commands from tasks that require connection or disconnection of the data link are routed to the X.21 module. The X.21 module 11 has the ability to modify line supervisor module 12 to cause it to route character interrupt control to the X.21 module 11 instead of to the normal SDLC/BSC protocol modules 12 and 13. This is done by the X.21 module for the X.21 data link connect/disconnect phase shown symbolically by dashed lines 14. In this phase, all data transfers to and from the data communication equipment 15 are controlled by the X.21 module. Interrupt control is restored for the actual SDLC/BSC data transfers. In this phase, data transfers to and from the remote data terminal equipment 16, 17 are controlled by SDLC/ BSC microcode for modules 12, 13. In this way, the X.21 module has the ability to gain control of the data communications line to perform the character synchronous X.21 connect/disconnect function that is based on the international alphabet number 5 character code.

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