Memory width expansion – composing an 8 k × 8 from 8 k × 1 devices How many separate 8 k × 1 RAM chips are required to build a memory with word capacity 8 k and word length 8 bits (i.e., 8 k × 8)?
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AEight
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BFour
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CTwo
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DOne
Answer
Correct Answer: Eight
Explanation
Introduction / Context:Designers often widen memory data paths by placing multiple narrow RAM ICs in parallel. This question tests the principle of data width expansion without changing address depth.
Given Data / Assumptions:
- Available IC: 8 k × 1 (8,192 addresses, 1 data bit each).
- Target memory: 8 k × 8 (8,192 addresses, 8 data bits each).
- All devices share the same address and control lines to maintain identical depth.
Concept / Approach:To increase word length from 1 bit to 8 bits while keeping the same number of addresses, connect eight identical 8 k × 1 chips in parallel on A0..A12 and control pins. Each chip supplies one bit of the 8-bit data bus (D7..D0).
Step-by-Step Solution:
Depth required = 8 k; each chip provides 8 k → match.Width required = 8 bits; each chip contributes 1 bit.Number of chips = 8.Verification / Alternative check:A quick block diagram shows eight chips with common address and enable signals, outputs OR rather “wired” onto separate data lines forming an 8-bit bus.
Why Other Options Are Wrong:
- Four / Two / One: Would result in 4, 2, or 1 data bits per word, not the required 8.
Common Pitfalls:
- Confusing “depth increase” (cascading addresses) with “width increase” (parallel data lines).
Final Answer:Eight