Memory training isn’t a single sprint — it’s a martial art, mastered stage by stage. Each stage tunes one kind of signal, and the order can’t be shuffled: first right yourself, then right the other; first the mantra, then the moves; first observe, then strike; first coarse, then fine; and finish with grand mastery. Cultivate out of order and your qi deviates — all your work goes up in smoke.
The training map
| Stage | Inner art | What it tunes |
|---|---|---|
| Pre-training prep | Right yourself | Calibrate your own analog circuits (Xover / SenseAmp / CTLE), exit DDRIO reset. |
| Command / Address | The mantra | CA/DCS/CS/QCS/QCA, through the RCD |
| Read direction | Open the third eye | Receive Enable → 2D Centering → DFE |
| Write direction | Strike | Write Leveling → 2D Centering → DFE |
| Per-bit de-skew | Unblock the meridians | Remove each bit’s own skew |
| Finishing optimizations | Grand mastery | SenseAmp / RxJitter / RoundTrip / Turnaround / PPR |
Vref isn’t a stage of its own — it’s the Y axis of 2D Centering, and the Vref dimension of command training. More when we get to 2D.
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Why this order?
① Right yourself before you right the other.
Before training the DRAM, calibrate your own analog circuits. If your own ruler isn’t calibrated, using it to calibrate someone else’s ruler (the DRAM) is nonsense.
② The mantra before the moves.
Command/address is the mantra; data is the moves. Recite the mantra wrong and every move goes sideways. And the command lines have no doorbell riding along — they must be trained alone, first.
③ Observe before you strike.
Write training means “write it in, then read it back to check the answer” — so the read path must first become a sharp pair of eyes. Only a sharp eye can tell the true bead from a fake one.
④ Coarse before fine.
Every pass starts by sweeping for a rough position, then brings up the equalizer, then fine-tunes. DFE changes the eye’s shape, so after fitting DFE the eye’s center moves again and you must re-center — that’s why Pre DFE 2D Centering and Post DFE 2D Centering always come in pairs.
⑤ Grand mastery comes last.
The finishing touches are the icing — there’s only margin to squeeze once the earlier power is in place. Not just SenseAmp: also RxJitter cancellation, RoundTrip latency, Turnaround timing, and PPR repair — all squeezing more out of a system that already works.
The real training trace
PreTrainingInit → HmrcScadExit ← ① prep (exit reset)
RCD DCS → CS → RCD DCS Vref/DFE ← ② mantra (command foundation)
RCD DCA TCO → Duty Cycle → DFE Tap1/DFE ← ② mantra, advanced
Post Frontside → BCOM → QCS → QCA ← ② command bus
MDQS RecEn → RecEn → Read DQ-DQS Coarse ← ③ the eye (read direction)
DB Duty Cycle → Write Leveling → Write DQ-DQS ← ④ strike (write, after read)
Rx Jitter → Sense Amp Optimization ← ⑤ grand mastery
The golden rule
Training is a row of dominoes — each one has to fall right before the next can stand.