Service manual

1-46 AlphaServer GS80/160/320 Service Manual
1.11 Memory Module
The memory module uses SDRAM storage elements and CMOS
application specific integrated circuits (ASICs) for interface and
control logic. Each memory module holds two four DIMM memory
arrays.
Figure 1– 18 Memory Module
DIMMs
PLLs
MPD
MPA
MPD
PK0603
Memory module features include:
• Two memory arrays consisting of four DIMMs each.
• Read error detection of single-bit errors and the most prevalent 2-bit, 3-bit, and 4-bit
errors in SDRAM arrays. (Single-bit error correction can be enabled.)
• Write data detection of single-bit errors written to memory.
• Write victim buffers allow write transactions to be in a “pre-directory lookup” state
freeing the write transaction commander to continue processing without waiting for
write confirmation. The command and data are placed in queues for later execution.