Browse Prior Art Database

Minicomputer System Components Interconnected Via a Serial Infrared Link

IP.com Disclosure Number: IPCOM000044934D
Original Publication Date: 1983-Jan-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 3 page(s) / 56K

Publishing Venue

IBM

Related People

Gfeller, F: AUTHOR [+2]

Abstract

The component units of a minicomputer system, such as a CPU station, a disk unit, and other peripheral devices including keyboards and printers, are interconnected by an infrared (IR) link, as shown in the drawing. An IR modem is provided for each component unit, and all device IR-modems must be in optical contact with the CPU station IR-modem, or vice versa constituting either a non-directional diffuse link or a line of sight link.

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Minicomputer System Components Interconnected Via a Serial Infrared Link

The component units of a minicomputer system, such as a CPU station, a disk unit, and other peripheral devices including keyboards and printers, are interconnected by an infrared (IR) link, as shown in the drawing. An IR modem is provided for each component unit, and all device IR-modems must be in optical contact with the CPU station IR-modem, or vice versa constituting either a non- directional diffuse link or a line of sight link.

The IR link replaces cables, connectors and associated electronic circuitry of all intercomponent data paths. This saves not only hardware cost, but also solves cabling problems.

In operation, the CPU station polls all devices centrally. The format and protocol used are straight SDLC (synchronous data link control).

Disk unit commands and responses.

Information transfer between the CPU station and the disk unit is via SDLC I- frames (information frames) which carry commands, responses, and accompanying data. The disk unit contains a microprocessor which operates the SDLC secondary link station, interprets and generates I-frames and controls the disk drives accordingly.

The command and response I-frames to and from the disk unit are formatted as follows:
Verb + Adverb + Object.

The Verb field holds a command code which is closely related to the command code used in IBM System/370 channel programs for fixed block-length devices. The Adverb field (mandatory) and the Object field (optional) of a command frame contain the arguments passed with the command. Multiple (chained) commands are transmitted as a sequence of SDLC I-frames.

The response frames from the disk unit to the CPU station have exactly the same structure as the commands. Each command produces a response where the Verb and Adverb denote the operation to which this response belongs, and are just copied from the command. The Object field of a response contains resultant data. A command frame sequence thus produces a response frame sequence; both resemble each other, but carry different values in the respective Object fields.

The serial IR bus protocol and interface for the disk unit has the following properties and advantages: The direct-access storage device is operated by the CPU on a logical level. This allows for a product line of disk units which are functionally "plug" compatible, though there are differences in technology, cost and performance. The serial IR bus allows "block multiplexing"....