8085 microprocessor: “The temporary register in 8085 is a 16-bit register.” Evaluate the statement.
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ATrue
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BFalse
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CTrue only for CALL/RET
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DTrue only when paired with accumulator
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ECannot be determined
Answer
Correct Answer: False
Explanation
Introduction / Context:Internal registers of the Intel 8085 include 8-bit general-purpose registers (B, C, D, E, H, L, A), a 16-bit program counter and stack pointer, and some internal temporary registers. Distinguishing their widths is important for assembly and micro-architecture understanding.
Given Data / Assumptions:
- 8085 has 8-bit data bus and 16-bit address bus.
- General-purpose registers are 8-bit, pairable to form 16-bit operands (e.g., HL, BC, DE).
- Internal temporary registers (often denoted W and Z) are 8-bit each but can be used as a 16-bit pair.
Concept / Approach:
The phrase “the temporary register is 16-bit” suggests a single 16-bit register. In 8085, the internal temporary storage commonly referenced consists of two 8-bit registers (W and Z) used together as a 16-bit pair when needed; individually they remain 8-bit. Therefore, calling “the” temporary register 16-bit is inaccurate.
Step-by-Step Solution:
Identify internal temps: W and Z are 8-bit each.They are combined (WZ) to hold 16-bit addresses during certain operations (e.g., CALL/RET helpers).But there is no single monolithic 16-bit “temporary register.”Hence the blanket statement is false.Verification / Alternative check:
8085 microarchitecture documentation lists W and Z as 8-bit. The 16-bit entities are PC and SP, plus register pairs (BC, DE, HL) formed by two 8-bit registers.
Why Other Options Are Wrong:
- True: Overstates; not a single 16-bit temp register.
- True only for CALL/RET: Even then, it is a pair of 8-bit temps acting together.
- True when paired with accumulator: Accumulator pairing is not how a temp 16-bit register is formed.
Common Pitfalls:
Conflating register pairs with single registers; assuming address width (16-bit) implies internal temporary register width.
Final Answer:
False