System Board - HP b2600 Technical Reference

Block Diagram
System Board and PCI Board

System Board

The system board subsystem consist of a processor, system management chip, memory
controller and memory card slots, data buffers, address lines, data lines, I/O controller, PCI
bridges, LAN chip, Super I/O controller and SCSI controller chip. A few of these system
board components are discussed in the subsequent sections.
PA8600 Processor
This workstation uses a PA8600 processor running at 500 MHz. This processor has an
on-chip L1 cache and does not have an L2 cache controller. The on-chip cache consists of a
0.5 MB I-cache and a 1 MB D-cache that are both four-way associative. The PA8600
consumes 80 watts (2.0V at 40A)) in a 544-pin LGA. Note that the PA8600 is socketed.
Memory and I/O Controller
The Memory and I/O Controller is a 664-pin ceramic LGA and generates about 20 watts.
This chip communicates with the PA8600 processor via the 64-bit turbo runway bus. The
Memory and I/O Controller chip transfers data on both edges of the 120 MHz clock giving a
maximum peak/sustainable bandwidth of 1.9/1.5 GB per second to the processor.
The Memory and I/O Controller communicates with the I/O subsystem via data lines. A
data line, in this context, is a 10-bit (18 total signals), 133 MHz point-to-point bus. The PCI
bridge chips can convert one data line to a PCI 1x or PCI 2x bus and it can convert two
data lines to a PCI 4x bus. The B2600 uses two data lines and two PCI bridges in its I/O
subsystem.
The Memory and I/O Controller chip communicates to the memory using separate address
and data buses.
Memory Components
The B2600 uses a 120 MHz synchronous DRAM memory subsystem. This workstation
supports four DIMMs using one Memory and I/O Controller and two data buffers. The
address bus connects the Memory and I/O Controller directly to the DIMMs. The two data
buffer chips split the single high-speed data buses from the Memory and I/O Controller
chip into two slower (single edge of 120 MHz clock) data buses that can support up to four
DIMMs per bus. The B2600 only uses one of these data buses. The high-speed data bus
connects the Memory and I/O Controller chip and the data buffers clocks on both edges and
has a maximum peak/sustainable bandwidth of 1.9/1.5 GB per second.
DIMMs need not be installed in pairs. The B2600 will support 256 MB, 512 MB and 1 GB
DIMMs. Installing four 256 MB DIMM cards allows the B2600 to reach a maximum
memory capacity of 1 GB. Using four 512 MB DIMM cards allows the B2600 to reach a
maximum memory capacity of 2 GB, and using four 1 GB DIMM cards allows you to reach
a maximum memory capacity of 4 GB.
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