International Business Machines Corporation

Hironao Sone

Kazuo Sekiya

Hiroshi Ishikawa

Yoshihisa Kanada

Yoshinao Kobayashi

Yeong-Chang L Lien

Yeong-Chang Lien

To enable a computer system such that each local arbiter is supposed to output its own priority as the right to use the bus on a common arbitration bus through open-collector-type drivers to determine a winner in arbitration, to expand the bus by way of a channel different from bus signal lines. Certain representation features 73 and 79 having the functions of a local arbiter that represent the arbitration level of the other bus are provided in both a primary system and a secondary system linked via a channel in a signal transmission mode different from the signal transmission mode of the bus. Arbitration is first conducted on each of the buses of the primary and secondary system to determine winners in arbitration. Notification of the arbitration level of each winner is made through a channel to the representation feature on the other bus. After this notification, arbitration is conducted once again between a winner in arbitration on each bus and the representation feature representing the arbitration level of the other bus to determine a final winner.

Computer system and system expansion unit

To smoothly transmit a plurality of types of data with different priorities via the same signal transmission path. Four-bit data showing the state of a bus are converted into six-bit data between a personal computer and an extension box connected by two optical-fiber links in accordance with a predetermined code system in a normal state, and the converted six-bit data are superimposed on a packet by using a field consisting of six bits as a single unit and serially and sequentially transmitted in order to transfer the state of the bus. When bus arbitration is performed by one system and an ARB level is determined, an interrupt start code not defined by the predetermined code system is prefixed to ARB-level data and an interrupt cancellation code not defined by the code system is suffixed to ARB-level data so that data can be transmitted by asynchronously interrupting packet transmission. Thereby, the ARB level determined by the primary-side system is instantaneously transferred to the secondary-side system.

Data communications method and system coupling device

To enable wired-OR signal lines to be connected without interlock in a bus linkage unit for connecting the bus of a computer system with the bus of an expansion device or the bus of another computer system through a signal transfer path in which the signal mode is different from those of the buses. A shadow register 46 that acts on the level of wired-OR signal line 51 of the other bus is provided in each system. The level of wired-OR signal lines in each system is sent to the shadow register of the other system through a communication path. When the shadow register of the system is at a predetermined level, said system will not send the level of said wired-OR signal line to the other system. Interlock is eliminated by avoiding repetition of level transfer echoes between both systems in this way. Both systems are further provided with a shadow-shadow register 47 for forming a mirror image of the shadow register of the other system. A predetermined level will be sent to the shadow register of the other system based on the nonconformity between the level of the shadow-shadow register in each system and the level of wired-OR signal line of said system.

System having different signal transfer modes for detecting and

A computer having slots for attachment of expansion adapters contains means enabling the system formed by the computer and attached adapters to reconfigure automatically, when an adapter is either inserted into an empty slot or removed from an occupied slot, while the system is fully powered and in an application running state. Insertion of an adapter into an empty slot is detected by an adapter detection mechanism. The mechanism signals a programmed resource manager element in the computer, via an interrupt or the like, and the resource manager then sequences the computer and inserted adapter through a series of mechanical and electrical reconfiguring operations. In these operations, the adapter is physically locked into place relative to the slot, supplied with power from a source in the computer, and signal conduction paths through the slot are activated. Thereafter, attribute information stored by the adapter is read out to the computer and the computer conducts a setup process to modify its configuration information to establish proper communication levels and addresses for the adapter commensurate with then active resources of the system. To remove an installed adapter, a user issues an adapter removal request to the resource manager, via an adapter removal button. In response to such request, the resource manager checks the running state of the adapter. If a data transfer is being conducted relative to the adapter, further operation in response to the request is delayed until the transfer is completed. When the request can be handled, the resource manager electrically isolates and mechanically releases the adapter, allowing the user to remove it.

Growing community of inventors

Yokohama, Japan

Hironao Sone