RAM speed — key timing parameters Which timing parameters primarily set a RAM device’s operating speed?

Introduction / Context:
RAM performance is defined by how fast it can complete read and write cycles. Datasheets provide multiple parameters, but two composite timings dominate throughput: read cycle time and write cycle time. Recognizing them helps you estimate maximum sustainable bandwidth.

Given Data / Assumptions:

• tRC: Read Cycle time (minimum time between successive valid reads).
• tWC: Write Cycle time (minimum time between successive valid writes).
• Other parameters specify internal delays to outputs or control pin setup/hold relationships.

Concept / Approach:
Throughput is bounded by how quickly back-to-back operations can finish. tRC and tWC capture the end-to-end latency constraints for reads and writes. While access time (tACC, tAA) and output delay (tCO, tOD) are important, the full cycle times dictate the maximum operation frequency in many simple interfaces.

Step-by-Step Solution:
Identify high-level throughput constraints: cycle times.Recognize tRC (reads) and tWC (writes) as the primary limits.Therefore, these two parameters primarily determine operating speed.

Verification / Alternative check:
Timing diagrams show that even if access time is short, violating tRC/tWC results in unstable or undefined operations; thus cycle times cap the effective frequency of consecutive operations.

Why Other Options Are Wrong:

• tACC, tAA, tACS, tCO, tOD: Important, but they are subcomponents; they do not alone define the maximum sustained read/write rate.

Common Pitfalls:

• Equating fast access time with high throughput without considering cycle time constraints.
• Ignoring bus turnaround and control pin setup/hold that also factor into tRC/tWC.

Final Answer:
tRC and tWC