8051 Microcontroller Architecture|RISC And CISC CPU Architectures|HARVARD & VON- NEUMANN CPU Architecture

8051 Microcontroller Architecture: In this post, 8051 Microcontroller Architecture,CISC Vs CISC, and Harvard Vs Von- Neumann CPU Architecture is explained.

Contents

What is a Microcontroller?

A microcontroller (MCU for microcontroller unit) is a small computer on a single VLSI integrated circuit (IC) chip.

Read : Microcontroller|Types of microcontroller

A microcontroller contains one or more CPUs (processor cores) along with memory and programmable input/output peripherals.

Program memory in the form of ferroelectric RAM, NOR flash or OTP ROM is also often included on chip, as well as a small amount of RAM.

Microcontrollers are designed for embedded applications, in contrast to the microprocessors used in personal computers or other general-purpose applications consisting of various discrete chips.

Addressing modes of 8051 Microcontroller|8051 Addressing Modes

More articles on Microcontroller is given at the last. Hope you check it

8051 Architecture

Here 8051 Microcontroller architecture is explained.

RISC and CISC CPU Architectures

Microcontrollers with small instruction set are called reduced instruction set computer (RISC) machines and those with complex instruction set are called complex instruction set computer (CISC).
Intel 8051 is an example of CISC machine whereas microchip PIC 18F87X is an example of RISC machine.

RISC Vs CISC Architectures

RISC	CISC
Instruction takes one or two cycles	Instruction takes multiple cycles
Only load/store instructions are used to access memory	In additions to load and store instructions, memory access is possible with other instructions also
Instructions executed by hardware	Instructions executed by the micro program
Fixed format instruction	Variable format instructions
Few addressing modes	Many addressing modes
Few instructions	Complex instruction set
Most of the have multiple register banks	Single register bank
Highly pipelined	Less pipelined
Complexity is in the compiler	Complexity in the microprogram

RISC Vs CISC Architectures

Von Neumann architecture vs Harvard architecture

Von-Neumann (Princeton architecture) and Harvard architecture

Von-Neumann Vs Harvard architecture

Von-Neumann (Princeton architecture)	Harvard architecture
It uses single memory space for both instructions and data.	It has separate program memory and data memory
It is not possible to fetch instruction code and data	Instruction code and data can be fetched simultaneously
Execution of instruction takes more machine cycle	Execution of instruction takes less machine cycle
Uses CISC architecture	Uses RISC architecture
Instruction pre-fetching is a main feature	Instruction parallelism is a main feature
Also known as control flow or control driven computers	Also known as data flow or data driven computers
Simplifies the chip design because of single memory space	Chip design is complex due to separate memory space
Eg. 8085, 8086, MC6800	Eg. General purpose microcontrollers, special DSP chips etc.