Altera QDRII SRAM Controller MegaCore Function - Manual (Page 37)

Altera Corporation MegaCore Version 9.1 3–5
November 2009 QDRII SRAM Controller MegaCore Function User Guide
Functional Description
When this initialization time has elapsed, the training group module
monitors the data coming back and checks for its validity.
When the training group module detects a pattern, it checks to see if it is
too early, too late, or on time. If the pattern is too early, the pointer moves
by one; too late, the pointer moves by one in the other direction. The
training group module retrains until the pointer is correct.
The RAM size ensures there is minimal latency, but there is enough slack
to compensate for the training pattern realignment.
Datapath
Figure 3–4 on page 3–6 shows the datapath block diagram.