DRAM refresh interval (legacy specification) What is the maximum time interval allowed before a dynamic RAM must be refreshed to avoid data loss (choose the typical legacy textbook value)?

Introduction / Context:
Dynamic RAM (DRAM) stores data as charge on tiny capacitors that leak over time. A refresh cycle periodically restores charge to prevent data loss.

Given Data / Assumptions:

• Question refers to a typical legacy value taught in basic electronics/logic courses.
• Older DRAM generations often cited a refresh window in the 2–8 ms range for the entire array.
• We are asked for the maximum allowable interval before refresh.

Concept / Approach:
If a range such as 2–8 ms is considered typical, the maximum of that range is 8 ms. Waiting longer than the specified maximum can allow charge to decay below reliable sensing thresholds.

Step-by-Step Solution:
Recall typical legacy range: a few milliseconds (often 2–8 ms).Select the highest limit among given options that matches this range.Choose 8 ms as the maximum allowable interval.

Verification / Alternative check:
Datasheets vary by generation and temperature. Later devices specify longer intervals (for example, 64 ms at nominal conditions), but the foundational teaching example commonly uses 8 ms as the maximum in the basic set.

Why Other Options Are Wrong:
2 ms and 4 ms are within the typical range but are not the maximum.10 ms exceeds the often-cited maximum for early DRAMs and risks data loss.16 ms is not among the original choices for many basic examples and is too long for the referenced range.

Common Pitfalls:
Mixing modern DRAM refresh specs (e.g., 64 ms) with classic textbook values targeted by this question.

Final Answer:
8 ms