Digital Equipment AlphaServer 1200, Руководство по обслуживанию

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System Overview 1-13
Memory Variants
Memory consists of two riser cards supporting 8 DIMM pairs. There are two DIMM
variants: a 32MB version and a 128MB version. Maximum memory using 32MB
DIMMs is 512MB and the maximum memory using 128MB DIMMs is 2GB. All
memory is synchronous
DRAM
Option Size Module Type Number Size
MS300-BA 64 MB 54-25084-DA
20-47405-D3 Synch. 9 4M x 72 =
32MB
MS300-DA 256 MB 54-25092-DA
20-45619-D3 Synch. 9 16M x 72 =
128MB
Memory Operation
Each DIMM in the pair provides half the data, or 64 bits plus 8 ECC bits, of the
octaword (16 byte) transferred on the system bus. DIMMs are placed in slots on the
riser cards and the riser cards are placed in the slots designated MEM L and MEM H
on the system motherboard.
NOTE: Memory in slot MEM L does not drive the lower 8 bytes, and memory in slot
MEM H does not drive the higher 8 bytes of the 16 byte transfer. Some bits
originating from MEM L are high order bits and some bits originating from MEM H
are low order bits.
Memory drives the system bus in bursts. Upon each memory fetch, data is
transferred in 4 consecutive cycles transferring 64 bytes.
Memory Configuration Rules
In a system, memories of different sizes are permitted, but:
•
DIMMs are installed and used in pairs. Both DIMMs in a memory pair must be
of the same size.
•
Each riser card receives one of the two DIMMs in the DIMM pair.
•
The largest memory pair must be in riser card slot 0.
•
Other memory pairs must be the same size or smaller than the first memory pair.
•
Memory pairs must be installed in consecutive slots.
•
Memory configurations that have a 64 MB pair in riser cars slot 0 are limited to
4 DIMM pairs or 256 MB for the system.