Abstract: A system for controlling an activity (program) switch on a scientific processor having an external executive control program. It includes the sequencing of the hardware at a macro level rather than at the more detailed lower levels previously used. This sequencing and control is accomplished by providing a macro code control, a macro code store and an instruction buffer write data selector interconnected with the existing macro logic and the main storage of the scientific processor to provide a system for starting, running and stopping the scientific processor by an activity switch which responds to interrupt signals to selectively shift from the receipt of data from the main storage to the receipt of data from the macro code store.

Abstract: A series of instructions N, N+1, N+2, etc. are issued by an instruction buffer 14 at a fixed clock rate in a pipelined method to parallel instruction flow path 6 and control word flow path 8, each path including a serial coupled holding register 20, 21, an instruction register 18, 19 and a function register 16, 17. If instruction N is a jump instruction, it and the related control word, when stored in the function registers 16, 17 causes the jump target instruction and the related control word of the jump instruction N to be entered into the holding register 20, 21. If the jump instruction N jump conditions are satisfied, the jump target instruction and related control word are written into the instruction registers 18, 19 and then into the function registers 16, 17 to be executed by the associated system.

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.