GATE CS 2002 Q1.13 — Machine Instructions and Addressing Modes

To identify which option is not a form of memory, let's analyze each choice:

• Instruction cache: A specialized high-speed memory block used by the CPU to store frequently accessed instructions to reduce access latency.
• Instruction register (IR): A dedicated, high-speed internal CPU register (which is a form of temporary storage/memory) that holds the instruction currently being decoded or executed.
• Translation Lookaside Buffer (TLB): A hardware cache (memory) that stores recent virtual-to-physical address translations to speed up virtual memory operations.
• Instruction opcode: An operation code is the part of a machine instruction that specifies the operation to be performed (such as ADD, SUB, or LOAD). It is a code representing an operation, not a physical storage or memory component.

Thus, the instruction opcode is not a form of memory.