Computer Architecture

Computer

• A computer is a programmable machine that executes instructions and responds to new instructions.

Computer Architecture

• Computer architecture involves the organization of components that comprise a computer system.
• It includes the semantics or meaning of operations that guide the computer’s function.
• Computer architecture specifies how software and hardware technology standards interact to form a computer system or platform.

Categories of Computer Architecture

System Design

• System design encompasses all hardware components in the system.
• This includes data processors aside from the CPU(central processing unit), such as the graphics processing unit and direct memory access.
• It also covers memory controllers, data paths, multiprocessing, and virtualization.

Instruction Set Architecture (ISA)

• Instruction Set Architecture (ISA) constitutes the embedded programming language of the CPU.
• It defines the CPU’s functions and capabilities based on the programming it can perform or process.

Microarchitecture

• Microarchitecture, also known as computer organization, defines data paths, data processing, storage elements, and how they’re implemented in the ISA.

Microprocessor

• A microprocessor has inputs, outputs, and a process.
• Microprocessors inputs and outputs consist of voltages that control external devices.
• The process analyzes input voltages to determine required output voltages based on previously entered instructions that are followed.
• Microprocessors act as the brain of a computer, performing all the work.
• It is a computer processor that integrates CPU functions on a single integrated circuit (IC) or a few ICs.
• Microprocessors were introduced in the early 1970s.
• The Intel 4004 was the first general-purpose microprocessor, used in personal computers.

Microprocessor Characteristics

Clock Speed

• Clock speed is the rate at which a microprocessor executes instructions.
• Microprocessors have a clock speed of approximately 3 GHz, which is the current technological limit due to heat generation.
• To combat this, manufacturers use multiple processors in parallel on a chip.

Word Size

• Word size refers to the number of bits a processor can handle in a single instruction.
• The first commercial microprocessor, Intel 4004, was a 4-bit processor with 4 input and 4 output pins.
• The number of output pins always equals the number of input pins.
• Most microprocessors use 32-bit or 64-bit architecture now.

Instruction Set

• The Instruction set is a command given to a digital machine to perform an operation on a piece of data.
• Examples of instructions include data transfer, arithmetic operations, logical operations, control flow, and input/output and machine control.

Microprocessor Components

Arithmetic and Logic Unit

• The Arithmetic and Logic Unit performs math computations like subtraction, addition, division, and Boolean functions.
• Boolean functions are a type of logic used for circuit designs.
• The ALU executes comparisons and logic testing.
• The processor sends signals to the ALU, which interprets instructions and performs calculations.

Registers

• Microprocessors have temporary data holding places called registers.
• Registers maintain data like computer instructions, storage addresses, and characters.
• Some computer instructions require the use of certain registers as part of a command.

Control Unit

• Control units (CUs) receive signals from the CPU, instructing them to move data.
• The control unit directs the arithmetic and logic unit.
• Control units consist of components like decoders, clocks, and control logic circuits, which together transmit signals to specific locations on the microprocessor.

Buses

• Microprocessors feature a system of buses to move data.
• Buses refer to classifications of wiring with specific tasks and functions.
• The data bus transfers data between the central processing unit and random access memory (RAM).

Cache Memory

• Advanced microprocessors use memory caches, which retain the last data used by the CPU.
• Memory cache speeds up the computing process, because the CPU doesn’t need to go to the slower RAM to retrieve data.
• A microprocessor is a small electronic circuit (typically 1/2 inch or 12mm across).
• Microprocessors are encapsulated in plastic or ceramic to protect them from moisture or abrasion.

Microcontroller

• A microcontroller (MCU or Microcontroller Unit) is a single Integrated Circuit (IC) used for specific applications to implement certain tasks.
• The microcontroller is used In products and devices that need automatic control, such as appliances, power tools, automobile engine control systems, and computers.
• In 1971, Intel and Texas Instruments introduced microprocessors.
• During 1970-1971, Gary Boone of Texas Instruments invented the microcontroller.

How they work

• A system requires inputs, outputs, and a process.
• Systems often have many inputs and outputs.
• Some outputs are required, and some are waste products.
• The first microcontroller was implemented in a four-function calculator.
• All computers and microcontrollers share a CPU that runs programs.
• The CPU loads programs. On desktops, the browser program is loaded from the hard disk.
• The computer uses RAM to store variables.
• Computers have input and output devices for communication, like keyboard, mouse, monitor and printer. -A hard disk is considered an I/O device.

Characteristics of a Microcontroller

• Microcontrollers are often embedded inside other devices like consumer products.
• They control the features or actions of the product, thus, are also known as "embedded controllers".
• Microcontrollers are dedicated to one task and run one specific program, usually stored in ROM.
• They are often low-power devices, consuming around 50 milliwatts compared to a desktop's 50 watts.

Differences between a MCU and a Logic Chip

• An MCU has a CPU, RAM, ROM and other peripherals embedded on a single chip.
• A Logic Chip lacks RAM, ROM etc, and has only the CPU packaged inside.

Microprocessors vs. Microcontrollers

• Microcontrollers are self-contained units containing a simple CPU or microprocessor.
• Microcontrollers are used for a single, pre-programmed application by the user.
• Microcontrollers are not especially powerful, use little power, and have little storage capacity.
• Microcontrollers operate only within their programmed tasks which defines their performance.
• Microprocessors are more complex and versatile in terms of function.
• Microprocessors are intended for general computing.
• Microprocessors have faster clock speeds, measured in gigahertz (GHz).
• Microprocessors are difficult and expensive to manufacture.
• Microprocessors require external components like RAM, I/O ports, data storage etc, which must be bought and connected separately.
• Microprocessors have a higher power draw and are less cost-effective.

Types of Microcontrollers

• Microcontrollers can be classified by bits, memory/devices, instruction set, and memory architecture.
• Examples of manufacturers of microcontrollers include Intel, Atmel, Dallas, Philips, and Siemens.

Classification According to Number of Bits

• In 8-bit microcontrollers, the ALU performs arithmetic and logic operations when the internal bus is 8-bit.
• Microcontrollers have a data bus width, the amount of data the MCU can process.
• An 8-bit microcontroller can process 8 bits at a time.
• Common data bus widths include 8-bit, 16-bit, and 32-bit MCUs.
• Examples of 8-bit microcontrollers are Intel 8031/8051, PIC1x, and Motorola MC68HC11 families.
• A 16-bit microcontroller performs with greater precision and performance than an 8-bit.
• An 8 bit microcontroller has a range of 0x00 - 0xFF (0-255) for every cycle.
• A 16 bit microcontroller has a range of 0x0000 – 0xFFFF (0-65535) for every cycle.
• A 32-bit microcontroller uses 32-bit instructions for arithmetic and logic operations.
• The 32-bit microcontrollers are used in automatically controlled devices including implantable medical devices and engine control systems.
• Examples for a 32-bit microcontroller include the Intel/Atmel 251 family, and PIC3x.

According to Memory/Devices

• An external memory microcontroller has a microcontroller unit that lacks all functional blocks on a chip.
• External memory devices of sizes can be added to increase code size.
• An embedded memory microcontroller has a microcontroller unit with all functional blocks available on a chip.
• Internal memory is the most cost-effective but least flexible memory type.

According to Instruction Set

• Complex Instruction Set Computer (CISC) involves coded instructions that take many clock cycles to execute.
• CISC allows single instructions to perform numerous low-level operations like loading from memory, arithmetic operations, and memory storage.
• Reduced Instruction Set Computer (RISC) uses wired instructions that take one or a few clock cycles to execute.
• RISC employs simple commands that can be divided into several instructions.

According to Memory Architecture

• Harvard Memory Architecture Microcontrollers have a dissimilar memory address space for program and data memory.
• Princeton Memory Architecture (Von Neuman) Microcontrollers have a common memory address for the program and data memory.

Components of a Microcontroller

• A microcontroller includes components such as the CPU, memory, timing and control, oscillators, ADC, special functioning blocks, timers/counters, DAC and interrupt control.

Microcontroller 8051

• The 8051 is an 8-bit family of microcontroller developed by Intel in 1981, and is very popular.
• Referred to as a system on a chip, it has 128 bytes of RAM, 4Kbytes of ROM, 2 Timers, 1 Serial port, and four ports on a single chip.

Memory Architecture of 8051

• The memory of 8051 is divided into Program Memory and Data Memory.
• Program Memory stores the program being executed, while Data Memory briefly stores data and results.
• The 8051 is easy to integrate and has been used in various devices like energy management, touch screens, automobiles, and medical devices.

Renesas Microcontroller

• Renesas is the newest automotive microcontroller family offering high performance with low power consumption.
• This offers safety and embedded safety features for advanced automotive applications, and the core structure supports high reliability and performance needs.
• RENESAS microcontroller stands for "Renaissance Semiconductor for Advanced Solutions."
• These microcontrollers offer the best performance for both microprocessors and microcontrollers.
• Renesas also include energy efficiency, performance, and solid packaging.
• The architecture uses a CISC Harvard architecture for high performance.
• The RL78 family is accessible from 8-bit to 16-bit microcontrollers, while the RX family is a 32-bit microcontroller.
• The RL78 family microcontroller is a low-power microcontroller, whereas the RX family provides high efficiency and performance.

AVR Microcontroller

• The AVR microcontroller, developed by Alf-Egil Bogen and Vegard Wollan from Atmel Corporation, utilizes a modified Harvard RISC architecture with separate memories for data and program.
• It shows AVR speeds are high compared to 8051 and PIC.
• The AVR stands for Alf-Egil Bogen and Vegard Wollan's RISC processor.
• The 8051s are 8-bit controllers based on the CISC architecture, and AVRs are 8-bit controllers based on the RISC architecture.
• The 8051s consume more power than AVR microcontrollers.
• 8051 is easier to program than the AVR.
• The speed of AVR is greater than the 8051 microcontroller.

PIC Microcontroller

• The PIC a peripheral interface controller was developed by General Instruments' microelectronics in 1993, and is software controlled.
• PIC is able to perform a lot of tasks and has made its way into phones, accessories, video and medical devices.
• The PIC has a RISC design,Its code is efficient, allowing it to run on less program memory, is low cost and has a high clock speed.

Comparison of Microcontrollers

• The 8051 utilizes 8-bit bus width for the standard core.
• The AVR, and PIC use 8 bits, 16 bits and 32 bits.
• UART, USART, SPI, and I2C are the communication protocols used in them.
• The speeds of the microcontrollers varies with 12 clock cycles , 4 clock cycles and just 1 clock cycle.
• While 8051 uses Von Neumann Architecture they offer Harvard Architecture which is modified
• All three uses almost the same popular manufacturers.

Advantages of Microcontrollers

• They are dependable, reusable, energy efficient, and cost-effective and require less time to operate.
• They are flexible and very small
• Their high integration decreases system size & cost.
• Interfacing is easy, with additional ROM, RAM & I/O ports.
• Many tasks can be performed, reducing the the human effect.
• It is simple to use and troubleshoot, and maintaining the system is also simple.
• Microcontrollers work like a microcomputer without any digital parts.

Disadvantages of Microcontrollers

• Programming is complex and there is electrostatic sensitivity
• Microcontrollers cannot interface with high-power devices.
• Their structure is more complex compared to microprocessors.
• Microcontrollers are used in microdevices and perform a limited number of executions simultaneously.