Abstract: Apparatus and methods for selectively controlling by window the number of overlay planes, the number of overlay palettes, and the overlay/underlay plane masks in a graphics video display system. A logic/multiplex control translates overlay and underlay data patterns from a multiple plane VRAM (Video Random Access Memory), referenced to the graphics system frame buffer, into window specific patterns. The window related translation is conveyed to conventional RAMDACs (Random Access Memory Digital-to-Analog Converters) for raster scan synchronized digital-to-analog conversion. The translation as provided by the controller is responsive to data selectively and dynamically written into a random access memory, thus providing translation of overlay/underlay data into window distinct and selective overlay/underlay palette functions.

Abstract: In a data processing system, a method for performing a series of operation sequence results and providing such results including the steps of (1) computing the results for each sequence of operations consecutively and (2) reading the results for the proceeding computations during the computation of a current operation result. This method further includes the use of registers for the temporary storage of the sequence results. During the computation of the operation sequence results, other registers are used in performing the sequence operations. The operations store parameters in a progressive fashion. In other words, the initial operations are performed in one set of registers while the final result from the sequence operation is stored in a different register. The result of a previous operation sequence computation is read from a register that is not being used during the computation of the current sequence operation.

Abstract: A data processing system including a processor that executes a plurality of instructions including at least one instruction that requires an external operation to be performed. The processor provides information for this external operation instruction to an external device and continues to execute instructions that do not require the results from this external operation. The external device receives the information from the processor, performs the external operation and provides the results to the processor. A further aspect of this data processing system is an interface that is interconnected between the processor and the external device. The processor provides the external operation information to the interface. The interface in turn provides the information to the external device and concurrently accesses data from the memory that will be required by the external device for performing the external operation.

Abstract: Apparatus is provided for the safeguarding of data recorded on disk and diskettes by tunnel erase magnetic head assembly which comprise a read/write transducer for magnetically recording data along tracks on said disk and a pair of magnetic erase transducers adjacent to the read/write transducer for limiting the width of the recorded data. The apparatus for safeguarding the recorded data comprises apparatus for sensing the activation of the erase and/or read/write transducer and apparatus responsive to such sensed activation for determining if the activation is erroneous.

Abstract: In a system for controlling a machine tool by a tool controller under the supervision of a central data processor, in which the controller transforms the data provided by the central processor into a format compatible with the machine tool, e.g., clock pulse encoded data format suitable for writing into and reading out of a serial storage magnetic memory device, a test system is provided wherein the central processor includes a simulation of the controller. This simulated controller gives the processor the capability of simulating and applying to the tool controller data in a format equivalent to that normally applied to the tool controller from the tool itself, e.g., a clock encoded data read output. The simulated controller also provides the central processor with the capability of receiving from the tool controller a tool control output in the format compatible with the control tool, e.g., clock encoded data and changing said data into an original format usable in the central processor.