Concurrent Computer Corporation

James E Hodge

Kenneth C Yeager

A multi-function high speed barrel shifter comprising three functional levels. The first level performs 1/4 word shifts by a selectable amount. The second level performs 1/8 word shifts on the portion of the word to be shifted and, where desired, fills the remainder of its output with fill bits. The third level performs 1/32 of a data word shift. All shifting and filling are controlled by an input control signal which specifies the operation, direction and shift amount. The circuit is easily complimented in LSI Technology and is easily cascaded to double the size of the data word handled thereby.

High speed barrel shifter

A multi-level priority micro-interrupt controller for a micro-program controlled computer handles a plurality of interrupt signals at a plurality of levels of priority, wherein only one interrupt signal for each level of priority may be active at any moment. When an interrupt occurs which has a higher priority than that of the interrupt currently being handled, the control store address of the next instruction to be executed is stacked and the interrupt handler subroutine for the higher priority interrupt is initiated. When an interrupt occurs which has a lower priority than that of the interrupt currently being handled, it is queued. After an interrupt has been handled, the stack is popped and execution is resumed at the control store address at the top of the stack. The control store address of the interrupt handler subroutine for a particular interrupt is decoded from the interrupt signals in two parts, the second part also being used to control the branching to the interrupt handler subroutine.

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Middletown, NJ, United States of America

James E Hodge