Abstract: A multi-system interconnect facility in which each central processor complex in the system has an assigned storage space for each other central processor complex in the system for use in communicating with each other central processor complex. The allegiance or association of systems to particular storage spaces is established when each system is initialized and enables a simple interface between user program(s) and message passing hardware consisting primarily of instructions for moving control and data blocks between the program addressable space and the hardware addressable space.

Abstract: A self-timed interface (STI) links two physically separated systems or nodes. A transmit state machine forms each word in a serial bit stream into a plurality of bytes and generates idle and data character sequences. Each byte is separately encoded in a run-length-limited code, along with its idle and data character sequences. Each of the plurality of bytes is transmitted on a separate conducting line along with a transmit clock signal that is also transmitted on a separate line. At the receiver, the data stream on each line is separately phase aligned with the clock, and bit aligned.

Abstract: An edge detector has a digital phase locking loop in which one of the signals (e.g., the data signal) is coupled to a delay chain that develops a series of incrementally phase delayed versions of the input. Adjacent phase delayed pairs are selected, one pair at a time, and are compared to the other signal (e.g., the clock signal) to determine if an edge of the clock falls between the edges of the data signal in the selected phase pair, or falls outside the edges of the selected phase pair, on one side or the other thereof. If the clock edge falls outside the selected pair, a control signal selects another pair for comparison and the process is repeated until, for example, the data edges are aligned with the positive going edge of the clock. With a clock frequency equal to twice data frequency, the data can then be sampled on the falling edge of the clock.

Abstract: A self-timed interface (STI) in which a clock signal clocks bit serial data onto a parallel, electrically conductive bus and the clock signal is transmitted on a separate line of the bus. The received data on each line of the bus is individually phase aligned with the clock signal. The received clock signal is used to define boundary edges of a data bit cell individually for each line and the data on each line of the bus is individually phase adjusted so that, for example, a data transition position is in the center of the cell.

Abstract: A shared channel subsystem has an input-output element for coupling each of a plurality of input-output controllers to each of a plurality of processor nodes by means of a self-timed interface (STI) in which a clock signal clocks bit serial data onto a parallel, electrically conductive bus and the clock signal is transmitted on a separate line of the bus. The received data on each line of the bus is individually phase aligned with the clock signal, providing a cost effective, modular input/output element.

Abstract: An enhanced input-output element has a self-timed interface (STI) in which a clock signal clocks bit serial data onto a parallel, electrically conductive bus and the clock signal is transmitted on a separate line of the bus. The received data on each line of the bus is individually phase aligned with the clock signal to provide a cost effective, modular, broadband, input/output element that can serve economically two channels and is modularly scalable to serve several hundred channels.

Abstract: A system for the transmission of information between elements of a data processing complex and a method for establishing such a system. Two elements of a data processing system are connected by a physical link comprising multiple conductors attached to transceivers at channels in each data processing element. Once the transceivers have been synchronized, commands and responses are exchanged which ensure that all of the transceivers in a channel are connected to the same channel on the other end of the conductor. If the transceivers are considered configured an entry is made in a Configured-Transceiver table. A search is made of an Allowed-Operational-Link table which contains sets of transceivers which are allowed to become operational links. The set of transceivers thus found, is compared against the Configured-Transceiver-Table to verify that all of the members of the set have been configured. If a match is found, this set of transceivers becomes an Intended-Operational-Link.

Abstract: An edge detector has a digital phase locking loop in which one of the signals (e.g., the data signal) is coupled to a delay chain that develops a series of incrementally phase delayed versions of the input. Adjacent phase delayed pairs are selected, one pair at a time, and are compared to the other signal (e.g., the clock signal) to determine if an edge of the clock falls between the edges of the data signal in the selected phase pair, or falls outside the edges of the selected phase pair, on one side or the other thereof. If the clock edge falls outside the selected pair, a control signal selects another pair for comparison and the process is repeated until, for example, the data edges are aligned with the positive going edge of the clock. With a clock frequency equal to twice data frequency, the data can then be sampled on the falling edge of the clock.

Abstract: A system and method for asynchronously transmitting data blocks, in parallel, across multiple fibers in a serial manner. Frame groups are provided as a mechanism to transmit associated data serially on each fiber and tie the data being transmitted together. The frame groups do not have sequence numbers, therefore, the receiver determines which frames are part of a frame group by the arrival times of the individual frames. The transceivers for each member of the parallel bus asynchronously achieve synchronism from either end of the fiber. Thus the need for a common clock is eliminated. The receivers on each side of the bus determine the relative skew for each conductor by performing skew measurements on a calibration message generated by the transmitters on the other side of the bus. When the skew on all conductors, viewed from both sides of the bus, has been determined, the skew values are exchanged across the bus, thus enabling the transmitters to set proper frame spacing.

Abstract: Buffers are provided in two elements between which data is to be transferred wherein both buffers are managed solely by the originator of the data transfer. Only one transfer is required to transmit a message, and a second transfer acknowledges the completion of the function because message delivery to the receiver is guaranteed under the implemented protocol. When a request is sent, a message timer is started at the sender. When the normal response for the request is received, the timer is reset; however, if the duration of the message operation exceeds the timeout value, a message-timeout procedure is initiated. When the cancel command is issued, a second timer is set. If this timer is exceeded, subsequent cancel commands can be issued. If subsequent cancel commands are issued, a cancel complete command must be sent and responded to.

Abstract: A system for the transmission of information between elements of a data processing complex and a method for establishing such a system. Two elements of a data processing system are connected by a physical link comprising multiple conductors attached to transceivers at channels in each data processing element. Once the transceivers have been synchronized, commands and responses are exchanged which ensure that all of the transceivers in a channel are connected to the same channel on the other end of the conductor. If the transceivers are considered configured and an entry is made in a Configured-Transceiver table. A search is made of an Allowed-Operational-Link table which contains sets of transceivers which are allowed to become operational links. The set of transceivers thus found, is compared against the Configured-Transceiver-Table to verify that all of the members of the set have been configured. If a match is found, this set of transceivers becomes an Intended-Operational-Link.

Abstract: A system and method for asynchronously transmitting data blocks, in parallel, across multiple fibers in a serial manner. Frame groups are provided as a mechanism to transmit associated data serially on each fiber and tie the data being transmitted together. The frame groups do not have sequence numbers, therefore, the receiver determines which frames are part of a frame group by the arrival times of the individual frames. In one embodiment, the transceivers for each member of the parallel bus asynchronously achieve synchronism at each end of the fiber. Thus the need for a common clock is eliminated. The receivers on each side of the bus determine the relative skew for each conductor by performing skew measurements on a calibration message generated by the transmitters on the other side of the bus. When the skew on all conductors, viewed from both sides of the bus, has been determined, the skew values are exchanged across the bus, thus enabling the transmitters to set proper frame spacing.

Abstract: A priority circuit handles requests by three components of a data processing system for access to several resources of the system that can be accessed one at a time on each operating cycle of the system. A logic circuit receives requests by the requesters and grants access to one requester on a priority basis. The logic circuit has means for establishing a particular priority sequence, and the priority circuit includes means for stepping the logic circuit through a cycle of different priority sequences. In a repeating cycle of these steps, each requester is given the highest priority at least once. In a specific embodiment, the stepping means is a counter and a cycle is called a counting cycle. The stepping means is responsive to a control code to establish a particular stepping sequence.

Abstract: A channel communicator CC has a storage array for holding an entry for each channel and for holding a busy vector and an interrupt vector that each have a bit for each channel. The CC is connected between the input bus and the output bus that connect the channels and an I/O processor IOP to processor main store. A message to the CC includes the ID of the channel that the message is to or from and the CC uses this ID as an address for accessing a channel entry or a bit in a vector. The message also carries a command that controls the CC to store a data portion of a message or to fetch a channel entry or a vector from the array and load it onto the output bus addressed to the IOP or to one of the channels. The command also controls addressing a particular one of the vectors. The CC also has means responsive to a command to perform a sequence of operations for testing the vectors and for testing fields of an entry in the array and for using the results of the test to control the execution of the command.

Abstract: Storage access requests are forwarded from plural input/output channels to shared main storage. An address word in each request designates the identity of the source channel (CHID) and "destination" address (of a doubleword space in storage relative to which one, two or four "data" words shall be transferred). EOT tag signal provides demarcation of requests and also uniquely identifies "1-wide" input (Store) requests. Quadword (QW) tag, presented with "4-wide" requests, enables the storage access system to use a single address in the request to locate two contiguous doubleword spaces in storage. Data tags (D1, D2), presented on a selective basis enable the access system to selectively steer (reorder the positions of) data words in an input request relative to word halves of the addressed space.

Abstract: The Channel Bus Controller (CBC) transfers information between groups of input/output channels and processor storage. Storage receives or dispenses two data words per access operation. Interfaces for transfers from the channel groups to the CBC are advantageously one word wide; since each output (fetch) request consists of a single request word. Information sent by each group is assembled into three-word units (a request word and zero, one or two data words) in a respective channel bus assembly register (CBAR). The assembled unit is passed from the CBAR to a respective area of an In Buffer array and from that array to storage. Zero filler words are inserted into unused data word positions. A channel request may be tagged to designate a transfer of four data words. If the transfer is an input the four data words are sent to the CBC with a single request word.