Unisys Corporation

Silverstorm Technologies, Inc.

William P Jordan

Todd M Rimmer

Duane J McCrory

Joseph David Coyne

Jeffrey E Dremann

A shared I/O subsystem for a plurality of computer systems. The shared I/O subsystem includes a plurality of ports that communicatively couple the computer systems to the shared I/O subsystem where each of the ports includes at least one corresponding bit in an adjustable span port register. Data packets arriving on the plurality of ports may be selectively provided to a span port based on a current state of the adjustable span port register.

System and method for span port configuration

A common peripheral device interface module is disclosed for use with the Unix (Unix is a trademark of AT&T) operating system which is flexible enough to support many types of disk or tape device drivers. A common disk module (CDM) is included. The CDM contains high level disk operation commands which may be used for common reference to each disk driver on the system. Routines within the CDM are accessed by the Unix system call interface through a series of operating system entry points. Additional routines are included with the pre-existing Unix operating system Disk I/O Subsystem to improve interfacing between this subsystem and the CDM. A common tape module (CTM) is used to perform high level tape operation routines. The Unix system call interface communicates with the CTM through a group of operating system entry points. Because there is no Unix operating system tape I/O subsystem, the CTM completely implements a tape I/O subsystem. To provide hardware portability, the CTM is configured to call a group of low level routines which have been incorporated into a device driver. Because of the large number of possible root disk device drives, the root disk device driver can be dynamically selected for the Unix operating system. Each controller which is resident within the system checks in with the operating system. The controller which checks in first with the operating system is used for booting up the system. Each controller which checks in is matched with an appropriate device driver. The matched device drivers are then used for disk I/O functions.

Peripheral device interface for dynamically selecting boot disk device

Apparatus for implementing input/output (I/O) operations in a computer system operating under the control of a UNIX* operating system includes a dedicated communications processor in addition to the main or host processor. These two processors communicate via a shared memory which may be independently accessed by each processor. The functions performed by the terminal I/O driver and the line discipline modules are divided between the host and communications processors. The communications processor performs all canonical processing of the data received from the terminal I/O devices. It also maintains a data structure that indicates the instantaneous status of each terminal I/O device. Using this data structure, the communications processor is able to operate in a substantially interrupt-free environment, polling only those I/O devices that are indicated, in the status data structure, as needing service. A message facility in the shared memory controls communication between the processors. Each processor sends messages to the other through a dedicated circular queue. To receive a message, a processor examines the sending queue of the other processor. Response messages are sent back to the sending processor using the same message buffer as was used for the original message.

Apparatus for implementing data communications between terminal devices

A common peripheral device interface module is disclosed for use with Unix (Unix is a trademark of AT&T) operating system which is flexible enough to support many types of disk or tape device drivers. A common disk module (CDM) is included. The CDM contains high level disk operation commands which may be used for common reference to each disk driver on the system. Routines within the CDM are accessed by the Unix system call interface through a series of operating system entry points. Additional routines are included with the pre-existing Unix operating system Disk I/O Subsystem to improve interfacing between this subsystem and the CDM. A common tape module (CTM) is used to perform high level tape operation routines. The Unix system call interface communicates with the CTM through a group of operating system entry points. Because of the large number of possible root disk device drives, the root disk device driver can be dynamically selected for the Unix operating system. Each controller which is resident within the system checks in with the operating system. The controller which checks in first with the operating system is used for booting up the system. Each controller which checks in is matched with an appropriate device driver. The matched device drivers are then used for disk I/O functions.

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Ephrata, PA, United States of America

William P Jordan