Browse Prior Art Database

Logical Control of Peripheral Systems

IP.com Disclosure Number: IPCOM000049816D
Original Publication Date: 1982-Jul-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 3 page(s) / 51K

Publishing Venue

IBM

Related People

Hinz, HC: AUTHOR [+3]

Abstract

A multiunit peripheral subsystem maintains configurational control using a single status store. Ohmic connections utilized in accordance with stored status eliminate switching circuits. One and only one of the programmable units in the subsystem can alter the configuration or transfer status at a given instant. A single control line, extending within each of these units, carries a control signal which indicates that one of its subunits is currently transferring status or exercising configurational control. Such subunit emits an indicating signal which all other subunits treat as an inhibit signal. Control is transferred between (among) the units using handshaking protocol via the status store.

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Logical Control of Peripheral Systems

A multiunit peripheral subsystem maintains configurational control using a single status store. Ohmic connections utilized in accordance with stored status eliminate switching circuits. One and only one of the programmable units in the subsystem can alter the configuration or transfer status at a given instant. A single control line, extending within each of these units, carries a control signal which indicates that one of its subunits is currently transferring status or exercising configurational control. Such subunit emits an indicating signal which all other subunits treat as an inhibit signal. Control is transferred between (among) the units using handshaking protocol via the status store.

A peripheral subsystem includes status store 10 which maintains peripheral subsystem status close to channel adapters 14, 15 (CAA-CAH) for rapid response as well as enabling dynamic reconfigurational control of the peripheral subsystem. In one embodiment, the peripheral subsystem includes first and second programmable storage control units 11 and 12, each connected to a programmable status store 10 (preferably PLAs (programmable logic arrays). The control units 11 and 12 are also denominated SCU 1 and SCU 2. Devices 13 (storage units (SUs)) are magnetic tape devices and magnetic storage disk devices enumerated from 0 through N. The PLA programmable channel adapters 14, 15 are connected to input output channels (not shown) of a host (not shown), as indicated by the double-headed arrows 16 and 17.

The control units 11 and 12 are also connected to the SUs 13 via a plurality of device adapters 20. 21. Each of the device adapters 20, 21 have a plurality of circuits, one circuit for each of the SUs 13. A non-switched connection is made between each SU and a corresponding circuit in both adapters 20, 21. Such ohmic connections eliminate switching circuits heretofore employed for device accesses. The integrity of access to SUs 13 is maintained by status store 10 exerting influence over control units 11 and 12; i.e., subsystem integrity is based upon logic control derived from status signals stored in status store 10. The arrangement is also such that if control unit 11 were changing the dynamic configuration of the peripheral subsystem, as by selecting one 13, then at this time control unit 12 is in...