Abstract: A digital data processor has a central processing unit (CPU) that operates in plural addressing modes and or more adapters for receiving peripheral devices, e.g., PCMCIA devices. A first peripheral device service subsystem that handles communications between peripheral devices coupled to the adapters and software clients executing on the CPU in a first addressing mode. A second peripheral device service subsystem that handles communications between peripheral devices coupled to the adapters and clients executing on the CPU in a second addressing mode. The first peripheral device subsystem includes a configuration management section that allocates digital data processor resources, e.g., memory space, input/output channels, direct memory access (DMA) channels and interrupt (IRQ) levels, used for communications between the peripheral devices and clients, regardless of whether those clients are executing in the first or second addressing modes.

Abstract: A method and apparatus for operating a computer graphics system to perform a conditional test on a node in a graphics data structure during the traversal of the graphics data structure by a structure walker. The graphics system is operated to manipulate data contained in a memory to define a value for an operand that is to be tested. The system accesses the operand from the memory. A structure walker performs a test on the value of the operand during traversal of the graphics data structure. Depending upon the result of the test, the structure walker traverses one of several paths in the graphics data structure to create a graphics display.

Abstract: A stand-alone graphics workstation including a digital computer host and a graphics processing subsystem is disclosed. Address data relating to the graphics subsystem components is mapped into the host system virtual memory. The application processes residing in the host are thereby able to communicate directly with the graphics subsystem components, as, e.g. the structure memory, without the need of a direct memory access hardware arrangement or device drivers.

Abstract: A method for operating a computer graphics system to build custom nodes containing commands and data information that is stored in a data structure in the graphics subsystem. A host processor calls routines which build the custome nodes. A structure walker traverses the data structure and extracts the information from the data structure to pass it to the graphics subsystem for display. The use of custom nodes increases the flexibility of advanced graphics data structures bny allowing the creation of other data structures during execution of a first data structure.

Abstract: A host system executes one or more application programs which results in graphic data structures. These graphic data structures are then continuously and asynchronously traversed. Traversal requests by competing application programs are scheduled and performed so that each application views the graphics processing as its own. The traversal and ordering of traversal requests provide efficient use of resources for multiple application programs.