The GATE Grind

GATE 2026 IN – Question 56

Digital Electronics · Microprocessors and data acquisition · 2 marks · Multiple select

A 16-bit processor has 16-bit wide instructions and a few internal registers. Every 16-bit instruction is encoded in a fixed format with one operation code of 7 bits and up to three operands. The operand can be an internal register and each operand is encoded by 3 bits. All the internal registers can be specified in an instruction using three bits. The correct statement(s) for this processor is/are _____.

  1. The processor has 16 internal registers.
  2. The processor can support 128 unique operation codes (Opcodes).
  3. The processor has up to 8 internal registers.
  4. The processor can support 512 unique operation codes (Opcodes).

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Correct answer: (B) The processor can support 128 unique operation codes (Opcodes).; (C) The processor has up to 8 internal registers.

Explanation

A 7-bit opcode field represents at most $2^7=128$ distinct operation codes, so B is true and D is false. A 3-bit register field can identify at most $2^3=8$ internal registers, so C is true and A is false.

The three operand fields use $3\times3=9$ bits, leaving the stated seven opcode bits in the 16-bit instruction. Select **B and C**.