Compaq AlphaServer ES40 Manuel d'utilisateur télécharger pdf (Page 8)

Processor Module

An AlphaServer ES40 can have up to four CPU modules.

In addition to the Alpha 21264 chip, the CPU module has a

4-Mbyte second-level cache and a 2.2V DC-to-DC converter

with heatsink that provides the required voltage to the Alpha

chip. Power-up diagnostics are stored in a flash ROM on the

module.

PK0271

Processor Configuration Rules

•

The first CPU module is installed in CPU slot 0.

•

Additional CPUs are installed in the next available slot.

•

CPUs must be identical in speed and cache size.

Memory

Memory throughput in this system is maximized by the

following features:

•

Two 256-bit wide memory data buses

•

Very low memory latency (120 ns) and high bandwidth

with 12 ns clock

•

ECC memory

The switch interconnect can move a large amount of data over

two independent memory data buses. Each data bus is 256 bits

wide (32 bytes). The memory bus speed is 83 MHz. This

yields 2.67 GB/sec bandwidth per bus (32 x 83 MHz = 2.67

GB/sec). The maximum bandwidth is 5.2 GB/sec (2.67 x 2).

The design challenge was to maximize the capabilities of the

two wide data buses. Distributing the 256 data bits equally

over two memory motherboards (MMBs) was one solution:

simultaneously, in a read operation, 128 bits come from one

MMB and the other 128 bits come from another MMB, to

make one 256-bit read. Another 256-bit read operation can

occur at the same time on the other independent data bus.

In addition, two address buses per MMB (one for each array)

allow overlapping/pipelined accesses to maximize use of each

data bus. When all arrays are identical (same size and speed),

the memory is interleaved; that is, sequential blocks of mem-

ory are distributed across all four arrays.

256 Data + 32 Check Bits

Data

Bus 0

MMB2 MMB0 MMB3 MMB1

256 Data + 32 Check Bits

Address Arrays 2 & 3

Address Arrays 0 & 1

Data

Bus 1

C-Chip

To all eight D-ChipsTo all eight D-Chips

PK0272

1 2 3 4 5 6 7 8 9 10 11 12 13 ... 17 18

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Compaq AlphaServer ES40 Manuel d'utilisateur Page 8

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