Abstract: A computer is provided having a bus interface unit coupled between a processor bus, a peripheral bus, and a memory bus. The bus interface unit includes a processor controller linked to the processor bus for controlling the transfer of cycles from the processor to the peripheral bus and memory bus. Those cycles are initially forwarded as a request, whereby the processor controller includes a memory request queue separate from a peripheral request queue. Requests from the memory and peripheral request queues can be de-queued concurrently to the memory and peripheral buses. This enhances throughput of read and write requests; however, proper ordering of data returned as a result of read requests and data transferred as a result of write requests must be ensured. An in-order queue is also present in the processor controller which records the order in which the requests are dispatched to the peripheral and memory buses from the peripheral and memory request queues.

Abstract: A computer is provided having a bus interface unit coupled between a CPU bus, a PCI bus and/or a graphics bus. The bus interface unit includes controllers linked to the respective busses and further includes a plurality of queues placed within address and data paths linking the various controllers. A processor controller coupled between a processor local bus determines if an address forwarded from the processor is the first address within a sequence of addresses used to select a set of quad words constituting a cache line. If the address (i.e., target address) is not the first address (initial address) in that sequence, then the target address is modified so that it becomes the initial address in that sequence. Quad words are received in sequential order and placed into the queue. When the quad words are sent to the CPU, they are in toggle order.

Abstract: A computer is provided having a bus interface unit coupled between a CPU bus, a PCI bus and/or a graphics bus. The bus interface unit includes controllers linked to the respective buses and further includes a plurality of queues placed within address and data paths linking the various controllers. An interface controller coupled between a peripheral bus (excluding the CPU local bus) determines if an address forwarded from a peripheral device is the first address within a sequence of addresses used to select a set of quad words constituting a cache line. If that address (i.e., target address) is not the first address (i.e., initial address) in that sequence, then the target address is modified so that it becomes the initial address in that sequence. An offset between the target address and the modified address is denoted as a count value. The initial address aligns the reads to a cacheline boundary and stores in successive order the quad words of the cacheline in the queue of the bus interface unit.

Abstract: A computer system having a core logic chipset that functions as a bridge between an Accelerated Graphics Port ("AGP") bus device such as a graphics controller, and a host processor and computer system memory wherein a Graphics Address Remapping Table ("GART table") is used by the core logic chipset to remap virtual memory addresses used by the AGP graphics controller into physical memory addresses that reside in the computer system memory The GART table enables the AGP graphics controller to work in contiguous virtual memory address space, but actually use non-contiguous blocks or pages of physical system memory to store textures, command lists and the like. The GART table is made up of a plurality of entries, each entry comprising an address pointer to a base address of a page of graphics data in memory. The core logic chipset may cache a subset of the most recently used GART table entries to increase AGP performance when performing the address translation.