Abstract: A data processing system containing a vector processor and a scalar processor executes scalar and vector instructions which both comprise an operation portion and an operand pointer portion. In the vector instructions, however, the operand pointer portion contains an operand specifier which identifies a vector control word. Each vector control word contains, for the corresponding vector instruction, flags and vector operand pointers. The vector operand pointers specify vector registers in the vector processor. The flags contain additional information for the execution of the vector instructions.

Abstract: A main memory and cache suitable for scalar processing are used in connection with a vector processor by issuing prefetch requests in response to the recognition of a vector load instruction. A respective prefetch request is issued for each block containing an element of the vector to be loaded from memory. In response to a prefetch request, the cache is checked for a "miss" and if the cache does not include the required block, a refill request is sent to the main memory. The main memory is configured into a plurality of banks and has a capability of processing multiple references. Therefore the different banks can be referenced simultaneously to prefetch multiple blocks of vector data. Preferably a cache bypass is provided to transmit data directly to the vector processor as the data from the main memory are being stored in the cache.

Abstract: A central processor unit for a digital data processing system that processes prefetched instructions including a conditional branch instruction. The processor includes a fetch unit that has separate portions, one that retrieves operands and the other that retrieves instructions. When the fetch unit fetches a conditional branch instruction, it may continue to prefetch "branch not taken" instructions using the instruction fetch portion. The fetch unit initially uses the operand fetch portion to prefetch "branch taken" instructions. If it is determined that the branch is not taken, the prefetch operation is aborted, otherwise the prefetch operation is allowed to continue to provide the next instruction used by the processor.

Abstract: A mechanism for continually testing a first processor element in a suitable multiprocessor system in which at least first and second processor elements are connected to a common input bus to concurrently receive the same opcodes and operands. Both processors decode the opcodes; when an opcode indicates an operation to be performed by the second processor, the first processor responds by executing a diagnostic operation during the second processor's execution cycle, instead of remaining idle for that time. The particular diagnostic operation to be performed is selected from among a multiplicity of available diagnostic operations. The selection is dependent on the instruction to be executed by the second processor; that is, in order to not slow down the overall execution rate of the system, a diagnostic operation is chosen whose execution time is somewhat shorter than the execution time of the instruction being performed by the second processor.