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Accumulator based and register based architecture

Short answer

Accumulator-based architecture uses one special accumulator register that holds an operand and the result, e.g., 8085 ADD B. Register-based architecture uses many general-purpose registers as sources/destinations, e.g., ARM, MIPS, making instructions longer but faster.

What do you mean by accumulator based microprocessor? (What is register based and accumulator based architecture?)

Accumulator-based microprocessor

In an accumulator-based architecture, one special register, the accumulator (A), holds one operand of each arithmetic or logic operation and receives the result. The other operand comes from memory or another register. The 8085 is an example: ADD B means A ← A + B; the result is always in A.

Register-based (general-purpose register) architecture

In a register-based architecture, many general-purpose registers can be used as source and destination, so the instruction names the registers, for example ADD R1, R2, R3. Examples: MIPS, ARM, and, to a good extent, the 8086 (AX, BX, CX, DX can all be used as operands).

BasisAccumulator-basedRegister-based
Operand/resultOne operand and result in accumulatorAny register can be used
InstructionShort (one address implied)Longer (register fields)
SpeedMore data movement to and from accumulatorFaster, fewer memory transfers
HardwareSimpleMore complex
Example8085ARM, 8086 (partly)

✓ Answer checked by Claude Opus 5.5 (high effort)

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