i82845 Chipset

   It’s nobody’s secret the Intel Pentium 4 sales have been slow to rise due to high costs partly caused by the RAMBUS memory that remains up to three times more expensive than SDRAM memory. To boost Pentium 4 sales, popularize the platform and wipe out the Pentium III, Intel has recently introduced the Intel i845 chipset codenamed Brookdale. This chipset has got the specificity to support Pentium 4 processors and PC133 SDRAM memory. The i845 chipset is ready to support DDR memory, but Intel has decided to postpone the launch of the DDR model for a while. PC133 SDRAM features a one way channel bandwidth of 1 GB/s against 3.2 GB/s for Rambus memory. This lead to a math problem: indeed the Pentium 4 Quad pumped data bus delivers up to 3.2GB of data per second while the i845 chipset can support only 1GB/s. Due to this limitation the processor will most likely be starved for data resulting in poor performance the SDRAM very low latency time won’t be able to get a boost. With 256 MB of SDRAM actually priced around $30 it’s clear the i845 is a good deal to own an affordable Pentium 4 system.

Intel i845 Chipset

   The i845 chipset features a similar architecture than previous i81x models: it is composed of the MCH (Memory Controller Hub), and the 82845 (a kind of bridge). The i845 is obviously completed by the well known tried and tested ICH2 component (i82801BA) for total support of the most recent norms that is to say: 2xUDMA 100, AGP 4x with a maximum bandwidth of 1 GB/s, 4 USB 1.1 ports, PC 133 SDRAM (up to 512MB only), AC’ 97 2.1/MC97 and integrated 10/100Mb/s LAN features. Obviously the chipset includes two USB 1.1 controllers for a global bandwidth of 24 MB/s across the four USB ports.