Intel had everything planned in advance, knowing and releasing that the 845/SDRAM
would not be the perfect solution for the Pentium 4 due its memory bandwidth
limitation wouldn't be smart, they knew that their competitors were working
on DDR solutions that would offer similar chipsets in terms of features but
with higher potential from its memory subsystem thanks to DDR memory. Intel
was from the beginning designing the 845 to support DDR SDRAM, making the
845/SDRAM a temp solution for the Pentium 4 and giving more time for Intel
to continue working on their DDR support for the 845.
The South Bridge of the
845, ICH2 is the same as in the high end 850 chip which supports 4 USB 1.1
ports, ATA/100 support, CNR/AMR slots and a 6 channel AC”97 audio along with
a LAN interface.
Intel’s 845 built on hub architecture is used on the 845 well. The North Bridge features support for the Pentium 4 processor running at 400MHz
Quad Pumped Bus, supports 3GB of memory for PC133 SDRAM or 2GB of PC1600/PC2100
DDR SDRAM along with AGP4X. Note that as Intel positioned the 845 as a value
segment, ECC support is not available on the memory controller.
The 845D (DDR) and 845 (PC133) versions offer the same features; both share
the same ICH2 hub. The only difference between the 845D (DDR) and the 845
(SDRAM) is the memory controller which features support for DDR SDRAM.