Abstract: Instruction and data registers of processors of a multiprocessing computing system are joined and forked to allow processing in multiple modes of operation. When joined, the registers of the processors each contain a same piece of information, hence generating single instruction and data streams. In contrast, when forked, the registers of the processors contain different pieces of information, thereby generating multiple instruction and data streams. Additionally, information may be stored into partitions of memory and fetched and broadcast by processors local to the particular memory sections thereby resulting in a faster cycle time.

Abstract: A central time-of-day reference is integrated into a switch which interconnects I/O devices and host processors in a computer complex via fiber-optic links. A time reference oscillator in the switch serves to generate incrementing reference signals for the central reference and also provides a clock signal for the switch transmissions. Units to which the switch is attached obtain clock signals from their regenerated clocks which are synchronized to the time reference oscillator, and use the regenerated clock signals to control their local time-of-day references. Each unit periodically transmits a signal to the switch requesting a dynamic connection to the switch-based central time-of-day reference in order to receive a time of day message.

Abstract: An access method allows the separation of the command stream being sent to the control unit from the command stream interpreted by the channel. This access method allows the I/O subsystem to, first, reduce the number of interlocks required on the I/O interface. Second, the access method transfers as much of the I/O operation to the device as possible in a single block of data. Third, the access method allows the channel and device to "disconnect" from each other at the end of the transfer of this control information. The access method prepares the information to be transferred to the device in a single command. This is accomplished by means of a new flag in the CCW, using the spare bit in the flag field, called the DS flag. This flag allows the channel to operate as if it were a Chain Command (CC) from the view point of direction of data flow in the channel and a Chain Data (CD) from the view point of transferring control information across the interface.