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Simulation of Telecommunication Line Equipment

IP.com Disclosure Number: IPCOM000075041D
Original Publication Date: 1971-Jul-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

Geary, JI: AUTHOR [+2]

Abstract

Telecommunication terminals and line equipment may be simulated on an IBM System/360 which has been designed to operate as a terminal message interchange (TI). There are two parts to the simulation: 1) Line buffers and line buffer controls which simulate the communication line hardware. 2) Interfaces to the line buffers. The simulation utilizes a section of storage not accessible to the programmer through normal :TIinstructions. Line Buffers and Line Buffer Controls.

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Simulation of Telecommunication Line Equipment

Telecommunication terminals and line equipment may be simulated on an IBM System/360 which has been designed to operate as a terminal message interchange (TI). There are two parts to the simulation:
1) Line buffers and line buffer controls which simulate the

communication line hardware.
2) Interfaces to the line buffers. The simulation utilizes a section of storage not accessible to the programmer through normal :TIinstructions.

Line Buffers and Line Buffer Controls.

A 2048-byte section of auxiliary storage is divided into eight 256-byte buffers. Each buffer represents a communication line. The contents of the buffers represent the data and control information that would be transmitted over a communication line. Data and control information are passed between the line buffer and the processor in bytes under control of a Unit Control Quadword (UCQ). A UCQ is made up of 3 Unit Control Words (UCW) and a spare word. There is one UCQ for each line.

There are a displacement pointer and a byte counter associated with each line buffer. Each of these is an eight-bit byte located in auxiliary storage. The byte counter indicates the number of bytes that have been loaded into the line buffer by a Load Line Buffer (LLB) instruction. A Store Line Buffer (SLB) instruction stores the contents of the line buffer and sets the byte counter to zero.

The displacement pointer indicates which byte is being moved under control of the UCW. The displacement pointer is set to zero by the LLB instruction. This allows bytes to be received under UCW control starting from the first byte location in the buffer. The SLB instruction stores the contents of the line buffer into main storage and sets the displacement pointer to one. The displacement pointer is incremented by one under UCW control, each time a byte is transferred to or from the associated line buffer. Interfaces to the Line Buffers.

There are two means of interfacing to the line buffers. The first way of interfacing is by use of two program instructions, LLB and SLB. The LLB instruction is used to preload information into the buffer, which is to be used to simulate a communication line in the receive mode under UCW control. The SLB instruction is used to examine the information that had been transmitted to the buffer, which was used to simulate a communication line in the transmit mode under UCW control.

The second means of interfacing to the line buffer is under UCW control. This is described in IBM Systems Reference Library Manual "IBM 2969 Programmable Terminal Interchange Model 1", EPQ 888117:...