82561

The 82561 is a series of integrated circuits produced by Intel, designed for use in personal computers. Introduced in 1999, the 82561 series serves as a bridge between the CPU and the PCI bus, facilitating data transfer and communication between these components. The 82561 is a key component in the Intel 440FX chipset, which was widely used in early Pentium III-based systems.

The 82561 integrates several functions, including the PCI bridge, memory controller, and AGP (Accelerated Graphics Port) controller. This integration allows for efficient data transfer between the CPU, memory, and graphics card, contributing to the overall performance of the system. The 82561 supports various memory types, including SDRAM and DDR SDRAM, and can handle up to 4 GB of system memory.

The 82561 is a 32-bit PCI bridge, meaning it can transfer data at a rate of 33 MHz with a 32-bit data bus, resulting in a theoretical maximum transfer rate of 133 MB/s. This transfer rate is sufficient for the systems of its time, which typically used slower memory and storage technologies.

The 82561 was succeeded by the 82865, which introduced support for DDR2 SDRAM and other improvements. Despite its eventual obsolescence, the 82561 remains an important historical component in the evolution of PC architecture.