Abstract: A scarifier implement (1) for a hydraulic endless track vehicle, such as a Posi-track™ front loader (2). The implement (1) is attachable to a rear end of the loader (2). The implement (1) comprises a mount (3) for attaching the implement (1) to the loader (2), a body (4) hinged to the mount (3) and having a holder (20) for holding teeth or tines (5), and a drive assembly (6) extending between the loader (2) and the holder (20), for raising and lowering the teeth or tines (5) relative to the mount (3).

Abstract: An arrangement providing frame buffer memory for an output display by which single buffer and double buffered application programs may be run singly or simultaneously is described. An array of video random access memory sufficient to store data for at least two complete frames is configured in three different ways depending on the applications being run. When only programs designed to run on a single frame buffer are run, the memory is configured as a single frame buffer. When a single program designed to run on double frame buffers is run, the memory is configured as two visible frame buffers. When multiple programs designed to run on double frame buffers are run, the memory is configured into one visible and one invisible frame buffer. Additionally, apparatus for selecting data to be furnished to the display depending on whether the program operates as a single buffered program, a double buffered program, or a plurality of double buffered programs is provided.

Abstract: An arrangement for assuring the compatibility of versions of software produced for a particular computer hardware architecture including a hardware version register, apparatus for providing an indication of a version of hardware being utilized to operate a particular version of software, a software version register, apparatus for providing an indication of a version of software being run on the particular version of hardware, apparatus for comparing the version of hardware and the version software, and apparatus responsive to the results of the comparison for setting defaults and enabling circuitry in the hardware so that the version of software runs correctly on the version of hardware.

Abstract: A double buffered output display system including a first frame buffer, a second frame buffer, a multiplexor for furnishing data to an output display from one of the first or the second frame buffers, apparatus for storing a signal indicating that the multiplexor is to select a different frame buffer to furnishing data to an output display, and apparatus for furnishing the stored signal to the multiplexor only at the completion of a frame on a display and before a new frame commences.

Abstract: A method of allocating space in a frame buffer memory which is not used for storing pixels to be displayed currently including the steps of selecting a portion of the memory to be allocated for off-screen memory; determining the size of an area to be allocated; comparing the size of the area to be allocated with portions of the memory available to be allocated for off-screen memory using a memory allocation technique in which the least area considered is at least as great in either its horizontal or its vertical dimension as the greater dimension of the area to be allocated, the comparison being conducted in a pattern which consistently checks first a minimum area followed by three other minimum areas in an area having a size which is the next power of two larger in each dimension than the minimum area, then four more minimum areas in an adjacent area having a size which is the next power of two larger in each dimension than the minimum area than the minimum area in the pattern, the area selected for the seco

Abstract: A method for allowing direct graphics access to backup storage areas in frame buffer memory used for retained windows and controlled by a graphics accelerator which includes the steps of establishing a shared memory file in system memory for the backup storage area indicating that the retained windows area initially exists in excess frame buffer memory, the shared memory file having storage to indicate the use of the shared area by a process; generating a page fault whenever access to the graphics accelerator is attempted and the state of another process is stored on the graphics accelerator; and calling a device driver in response to the page fault to switch the context stored on the graphics accelerator to that of the process attempting the access.