---
title: "Accumulator based and register based architecture"
subject: "Microprocessor"
chapter: 6
key: "semester_4/microprocessor:accumulator-register-based-architecture"
source: https://www.bctengineer.com/q/semester_4/microprocessor/accumulator-register-based-architecture
site: BCT Engineering
---

# Accumulator based and register based architecture

Microprocessor · Chapter 6: Advanced Topics

- Asked in: 2074 Bhadra, 2 marks; 2072 Asoj, 2 marks (asked 2 times)
- Video: [Accumulator in Computer organization and architecture | Types of Organizations | well academy](https://www.youtube.com/watch?v=FovkoLq9F40) — Well Academy
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_4/microprocessor/accumulator-register-based-architecture
- Whole chapter: https://www.bctengineer.com/md/semester_4/microprocessor/chapter-6

## Question

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

## Answer

#### 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).

| Basis | Accumulator-based | Register-based |
|---|---|---|
| Operand/result | One operand and result in accumulator | Any register can be used |
| Instruction | Short (one address implied) | Longer (register fields) |
| Speed | More data movement to and from accumulator | Faster, fewer memory transfers |
| Hardware | Simple | More complex |
| Example | 8085 | ARM, 8086 (partly) |

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. In an accumulator-based processor, where do an arithmetic operation's result and one operand go?
   A. Both in the accumulator
   B. In any general register
   C. In memory only
   D. On the stack
   Answer: A. ADD B means A <- A + B. (Key point: Accumulator-based)

2. What characterises register-based architecture?
   A. One special register is always used
   B. Memory is always the destination
   C. Many general-purpose registers can be source and destination, named in the instruction
   D. Instructions are implicit
   Answer: C. e.g. ADD R1, R2, R3. (Key point: Register-based)

3. Which pair is correct?
   A. 8085 accumulator-based; ARM register-based
   B. 8085 register-based; ARM accumulator-based
   C. Both accumulator-based
   D. Both register-based
   Answer: A. The 8085 uses accumulator A; ARM and MIPS use general registers. (Key point: Examples)

## Related in Microprocessor

- [Microprocessor based system and bus organization](https://www.bctengineer.com/question.md?key=semester_4%2Fmicroprocessor%3Amp-based-system-bus-organization) — Microprocessor, chapter 1, asked 5×
- [8086 architecture and programmer registers](https://www.bctengineer.com/question.md?key=semester_4%2Fmicroprocessor%3A8086-architecture-registers) — Microprocessor, chapter 3
- [Short note: Register Transfer Language](https://www.bctengineer.com/question.md?key=semester_4%2Fmicroprocessor%3Ashort-note-rtl) — Microprocessor, chapter 1
- [Internal architecture of 8086](https://www.bctengineer.com/question.md?key=semester_4%2Fmicroprocessor%3A8086-architecture-block-diagram) — Microprocessor, chapter 3, asked 4×
- [Compare RISC and CISC architecture](https://www.bctengineer.com/question.md?key=semester_4%2Fmicroprocessor%3Arisc-vs-cisc) — Microprocessor, chapter 6, asked 4×
- [Internal architecture of 8085](https://www.bctengineer.com/question.md?key=semester_4%2Fmicroprocessor%3A8085-architecture) — Microprocessor, chapter 2, asked 3×

## Related in other subjects

- [Features of microprocessor based instrumentation](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Ambi-features) — Instrumentation II, chapter 1, asked 4×
- [Microprocessor-based transmission line protection](https://www.bctengineer.com/question.md?key=semester_6%2Fswitchgear_and_protection%3Amicroprocessor-line-protection) — Switchgear and Protection, chapter 8, asked 2×
- [Types of microprocessor based instrumentation systems](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Ambi-types) — Instrumentation II, chapter 1
- [Microprocessor relaying via generator field current](https://www.bctengineer.com/question.md?key=semester_6%2Fswitchgear_and_protection%3Amicroprocessor-generator-field) — Switchgear and Protection, chapter 8