Subelement D: Display & Control Systems - 10 Key Topics – 10 Exam Questions— Topic 35: Memory Systems
Question 8-35D2
Element 8 (RADAR)While troubleshooting a memory problem in a raster scan RADAR, you discover that the “REFRESH” cycle is not operating correctly. What type of memory circuit are you working on?
Explanation
Dynamic Random-Access Memory (DRAM) stores each bit of data as an electrical charge in a tiny capacitor. These capacitors, due to inherent leakage, lose their charge over time. To prevent data loss, DRAM requires periodic "refresh" cycles, where the data is read and then rewritten to restore the charge levels. If the refresh cycle fails, the memory will eventually lose its stored data, leading to problems like those described.
SRAM (Static Random-Access Memory), in contrast, uses latches (flip-flops) to store data, which hold their state as long as power is supplied and do not require refreshing. ROM (Read-Only Memory) and PROM (Programmable Read-Only Memory) are non-volatile memories where data is permanently or semi-permanently stored, and refresh cycles are not part of their operation for data retention.
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