Abstract: A method and system for providing a plurality of host systems shared access to data files from a file server. The method includes monitoring a control file for updates, the control file located within a corresponding host directory located within the file server; receiving a request for access to a data file stored on the file server, the access request being written to the control file, the access request including a requested data file operation; performing the requested data file operation in response to the control file being updated with the access request; creating a status file in the host directory in which the requested data file operation was performed upon completion of the requested data file operation; writing status data in the status file, the status data including a result of the performance of the requested data file operation; and allowing access to the host directory in which the requested data file operation was performed in response to the status data being written to the status file.

Abstract: A method and system for providing a plurality of host systems shared access to data files from a file server. The method includes monitoring a control file for updates, the control file located within a corresponding host directory located within the file server; receiving a request for access to a data file stored on the file server, the access request being written to the control file, the access request including a requested data file operation; performing the requested data file operation in response to the control file being updated with the access request; creating a status file in the host directory in which the requested data file operation was performed upon completion of the requested data file operation; writing status data in the status file, the status data including a result of the performance of the requested data file operation; and allowing access to the host directory in which the requested data file operation was performed in response to the status data being written to the status file.

Abstract: A method of and apparatus for improving the scheduling efficiency of a data processing system using the facilities which maintain coherency of the system's level cache memories. These efficiencies result from monitoring the cache memory lines which indicate invalidation of a cache memory entry because of a storage operation within backing memory. This invalidity signal is utilized to generate a doorbell type interface indication of a new application entry within the work queue.

Abstract: A method of and apparatus for improving the efficiency of a data processing system employing multiple dayclocks using the facilities which maintain coherency of the system's level cache memories. These efficiencies result from dedicating a separate individual dayclock to each of the multiple instruction processors within the data processing system thereby decreasing access time and user queuing. These individual dayclocks are each incremented at one microsecond intervals. However, these individual dayclocks require periodic synchronization to avoid system level time-tagging problems. This synchronization occurs at 20 microsecond intervals using the cache coherency maintenance hardware of the system.

Abstract: Data transfer scheme wherein data transfer rates can be effectively doubled with no increase in the clock speed of the interface. This is accomplished by allowing more than one data transfer to occur on a single clock cycle. This transfer scheme increases the transfer rate of the interface by multiplexing two data groups on the same interface. These data groups are transmitted from a source phase latch at approximately the same time as two strobe signals which have low skew with respect to the data. The master and slave strobe signals are logically combined to create an even latch enable signal and an odd latch enable signal that are used to latch and de-multiplex the multiplexed data groups at a receiving end of a pair of flow-though source synchronous latches.

Abstract: A method and apparatus for efficiently reading a day clock and storing the value into main storage. An advantage is that the memory storage command can request the main storage control to read a current day clock value and store the value into a main storage location specified by the requesting processor while allowing the requesting processor to continue processing other commands. A further advantage is that the requesting processor does not have to wait for the return of a day clock value or the generation of a main storage write request which may reduce the number of main storage I/O bus requests and bus transfer cycles over that normally required to transfer the day clock value to the requesting processor and then back to main storage.

Abstract: A network input/output processing system for sending and receiving messages between a large scale computer system and associated communications networks. Executive operating system services provide access to a control table, an input queue, and an output queue stored in the computer system's main memory. A network input/output processor responds to requests by application programs, through a communications program, for receiving input from and sending output to a network, concurrently with requests to communicate with directly attached peripheral devices such as disk drives, tape drives, and printers. The network input/output processor receives initialization, reset, and termination requests via the control table. Requests to receive input are received from the input queue. Input data is stored into buffers as directed by the input request. Requests to send output are received from the output queue. Output data is read from the buffers as directed by the output request.

Abstract: In a system wherein a central computer complex is connected through central control modules (CCM) and channel modules (CM) to the control units of peripheral subsystems, a first queue is maintained in a CCM for Start I/O Fast (SIOF) commands waiting to be accepted by the CMs connected thereto. After a CM accepts an SIOF command and passes it on to a control unit, the control unit may return to the CM a busy status which is then passed through to the CCM. The CCM maintains a control unit busy (CUB) queue and an entry is made therein when busy status is returned. When a control unit reports control unit end status to the CCM, the CUB queue is linked to the top of the SIOF so that the CMs may again be informed that the SIOF commands are available. The arrangement avoids two interruptions of the central computer complex to report first that the control unit is busy and then that the control unit is available.