Chapter 4 Computer Hardware

1. Chapter 4Computer Hardware 國立聯合大學　電子工程學系 蕭裕弘

2. Chapter Goals • 說明硬體與軟體的內容與差異 • 介紹個人電腦硬體的組成 • 說明 Von Neumann Architecture 的基本架構 • 說明主記憶體的組成與作業 • 說明 CPU 的組成與作業 • 說明輸入與輸出設備的種類與相關資料 • 介紹電腦未來的發展

3. 1. Introduction • Hardware • Equipment involved in the function of a computer. • Hardware is a comprehensive term for all of the physical parts of a computer. • Computer hardware consists of the components that can be physically handled. • The physical, touchable, material parts of a computer system.

4. Software • Software • The set of instructions a computer uses to manipulate data, such as a word-processing program or a video game. • Software provides instructions for the hardware to accomplish tasks. • These programs are usually stored and transferred via the computer's hardware to and from the CPU. • Software also governs how the hardware is utilized; for example, how information is retrieved from a storage device.

5. 2. 個人電腦系統單元 (PC system unit) • A system unit, also known as a base unit is the main body of a computer, typically consisting of: • A plastic or metal enclosure • The motherboard • A CPU (or processor) • A power supply • Cooling fans • Internal disk drives • The circuit boards that are plugged into the motherboard, such as video and network cards.

6. 主機板上的主要成員 • 晶片組 (chipset) • 可視為是電腦系統的心臟 • 匯流排 (buses) • 資料匯流排 (data bus) • 位址匯流排 (address bus) • 控制匯流排 (control bus) • 擴充槽 (expansion slots) • 加速圖形連接埠 (accelerate graphics port, AGP) • 週邊連接介面 (peripheral connection interface, PCI) • 其他常見的連接埠 (posts) • 通用序列匯流排 (universal serial bus, USB) 連接埠 • 序列連接埠 (serial ports) • 並列連接埠 (parallel port)

7. 匯流排 (Buses) • A bus is an electronic path on the motherboard or within the CPU or other computer component along which bits are transmitted. • Types of Buses: • Internal bus • The bus that moves data around within the CPU. • System bus • The bus that moves data back and forth between the CPU and memory. • Expansion buses • Buses that connect the CPU to peripheral devices. • Expansion buses are etched onto the motherboard, and connect the CPU to the expansion slots on the motherboard to which external devices may be connected. • ISA, PCI, AGP, USB, Firewire/IEEE 1394

8. Chipset and Buses CPU Front-Side Bus (FSB) AGP Bus System Bus AGP 8X/4X Memory North Bridge CPU Chipset PS/2 Parallel/Serial Floppy IrDA IDE Serial ATA USB 2.0/1.1 10/100M LAN AC’97 Audio Super I/O South Bridge PCI Bus

9. 0 1 0 0 0 0 0 1 01000001 Parallel vs. Serial Transmission • In parallel transmission, all bits in a single character are transmitted simultaneously. • Parallel transmission is primarily limited to transmission of data within a computer, between computers and between a computer and a printer. • It is fast compared to serial transmission but limited to shorter distances. • In serial transmission, bits are transmitted in a linear fashion, one after the other. • It is slower but can travel longer distances and is widely used.

10. 3. Von Neumann Architecture - 1 • The so-called von Neumann architecture is a model for a computing machine that uses a single storage structure to hold both the set of instructions on how to perform the computation and the data required or generated by the computation. • Such machines are also known as stored-program computers. The separation of storage from the processing unit is implicit in this model. • The architecture is named after mathematician John von Neumann who provided an early written account of a general purpose stored-program computing machine. The term Harvard architecture originally referred to computer architectures that used physically separate storage devices for their instructions and data.

11. Von Neumann Architecture - 2 Input Control Arithmetic & Logic Memory Output CPU Buses Control Input Output Arithmetic & Logic Memory CPU

12. 4. Memory • 記憶體 (memory) 是一種固態積體電路 (solid-state IC)，可用來作為資料的儲存場所。 • 主記憶體 (main memory or primary memory) • 主機板上常見的記憶體種類： • 隨機存取記憶體 (random access memory, RAM) • 動態隨機存取記憶體 (dynamic RAM, DRAM) • 靜態隨機存取記憶體 (static RAM, SRAM) • 唯讀記憶體 (read-only memory, ROM) • 遮罩式唯讀記憶體 (Mask ROM) • 可規劃之唯讀記憶體 (programmable ROM, PROM) • 快閃記憶體 (flash memory)

13. Memory Addressing • Memory is a collection of cells, each with a unique physical address. • When a block of data, instruction, program, or result of a calculation is stored in memory, it is stored into one or more consecutive addresses, depending on its size. Address 0000 0000 0000 0001 0000 0002 . . . FFFF FFFE FFFF FFFF Contents 1110 0011 1010 1010 0101 0101 . . . 1110 0011 1010 1010

14. 相關名詞 • Memory operation speed • Memory access time: • The average period of time (in nanoseconds) it takes for RAM to complete one access and begin another. • Access time is composed of latency (the time it takes to initiate a request for data and prepare to access it) and transfer time. • DRAM chips for personal computers have accessing times of 50 to 150 nanoseconds. SRAM has access times as low as 10 nanoseconds. • Parity check • Odd • Even Data bits Parity bit 0 1 0 0 1 1 0 1  1 0 1 0 0 1 1 0 1  0

15. 常見的 PC DRAM 規格 • Synchronous Dynamic RAM (SDRAM) • 比傳統記憶體的 clock rate 要快上許多。 • 和 CPU 的匯流排同步。 • 作業速度可達133 MHz。 • Rambus DRAM (RDRAM) • Internally similar to DDR SDRAM, but uses a special method of signaling developed by the Rambus Company that allows faster clock speeds. • 作業速度可達 1200 MHz。 • Double data rate (DDR) SDRAM • 一種雙倍速的 SDRAM，在每一個 clock cycle 的兩個觸發邊緣都能傳輸資料。 • 作業速度可達 200 MHz。

16. Memory Hierarchy A cache is a collection of duplicate data, where the original data is expensive to fetch relative to the cache. Registers Cache Volatile Main memory Non-Volatile Disks Tapes

17. 5. Central Processing Unit (CPU) • The central processing unit (CPU) is the part of a computer that interprets and carries out the instructions contained in the software. • Processor and microprocessor • In most CPUs, this task is divided between: • A control unit (CU): it directs program flow. • An arithmetic and logic unit (ALU): it performs operations on data. • Registers: a small amount of very fast computer memory used to speed the execution of computer programs by providing quick access to commonly used values. ALU Does all the computing CU Controls and checks Registers Workspace

18. Basic Structure of A CPU Instruction Register Program Counter Control Unit Registers Internal Buses Control Bus Control signals ALU Memory Address Register Address Bus Memory Data Register Data Bus

19. The Control Unit • The control unit coordinates the steps necessary to execute each instruction. • It causes each instruction to be moved to the CPU and then decodes it so that it can be executed. • It then tells the other parts of the CPU what to do and when to do it. • It is in overall charge of the movement of the vast amounts of instructions and data used by the computer. • Obviously, the movement of all these data must be coordinated and synchronized. To do this, the control unit uses a clock that issues control pulses. • The frequency of this clock is important as the more control pulses that it can generate in a given time, the faster data will be moved around the computer. • The clock is rated in megahertz - 1 megahertz means that 1 million control signals a second are generated. A cycle Clock

20. The Fetch-Execute Cycle • The instruction stage • Fetch the instruction. • Decode the instruction. • The execution stage • Execute the instruction. • Store the result to a register or memory. Decode Fetch Execute Store Machine Cycle

21. Microprogramming: design is simpler – problem of timing each instruction is broken down. Microinstruction cycle handles timing in a simple and systematic way. easier to modify slower than hardwired control Implementation of Control Unit • Machine code -> Control signals – how? • Early computers hardwired this. • RISC machines do as well. • Microprogramming is an alternative that allows for simpler machine hardware. • Hardwired: • composed of combinatorial and sequential circuits that generate complete timing that corresponds with execution of each instruction. • time-consuming and expensive to design • difficult to modify • … but fast

22. The Arithmetic and Logic Unit (ALU) • The Arithmetic and logic unit is responsible for doing the actual computing and so can be considered to be the brain of the computer. • The most common available operations are • The integer arithmetic operations of addition, subtraction, and multiplication. • The bitwise logic operations of AND, NOT, OR, and XOR. • Various shift operations, such as shift left, shift right, etc. • Typically, a standard ALU does not handle integer division nor any floating point operations. For these calculations a separate component, such as a divider or floating point unit (FPU), is often used. • The ALU takes as inputs the data to be operated on and a code from the control unit indicating which operation to perform, and for output provides the result of the computation. • In some designs it may also take as input and output a set of condition codes, which can be used to indicate cases such as carry-in or carry-out, overflow, or other statuses.

23. Bitwise Logic Operations

24. The Shift and Rotation Operations • Shift left • Shift right • Arithmetic shift left • Arithmetic shift right • Rotate left • Rotate right 0 1 1 0 1 1 0 0 0 1 1 0  0 0 1 1 01 1 0  01 0 0 1 0 0 0  11 0 0 1 0 0 1  1 1 0 0 1 0 0 1  0 0 1 1

25. Registers in CPU • General purpose registers (GPRs) • 儲存資料或指令。 • Special purpose registers • Program counter, PC (or Instruction pointer, IP) • 儲存下一個要被執行之指令的位址。 • Instruction register, IR • 儲存要被執行的指令。 • Memory address register, MAR • 儲存要送到主記憶體的位址。 • Memory data register, MDR • 儲存從記憶體讀取或是要寫入記憶體的資料。 • Flag register (or program status word, PSW) • 儲存 CPU 與 ALU 目前的處理狀態。 • ... Data bus Control bus Address bus MDR MAR PC IR Index registers Flag GPRs Stack pointer Accumulator

26. Measurements of CPU Performance • CPU clock rate: ~GHz • Throughput • The speed at which a computer processes data end to end. • MIPS • Million instructions per second • MFLOPS • Million floating operations per second • TPS • Transactions per second

27. 6. Input Unit • A device through which data and programs from the outside world are entered into the computer. • Input hardware consists of external devices that provide information and instructions to the computer.

28. Keyboards • A computer keyboard is a peripheral modelled after the typewriter keyboard. Designed to be used by a human to enter data by manual depression of keys. Most keyboards have characters engraved or printed on the keys, these usually represent characters selected from some language alphabet along with numbers and punctuation and other control keys. • The IBM PC keyboard with the QWERTY layout is nearly universal.

29. Pointing Devices • Mouse • Joystick • Trackball • Graphics tablet • Touch screens • Pointing stick • ...

30. Scanners and Related Devices • Optical scanner • Optical character recognition (OCR) • Optical reader • ...

31. Multimedia Input Devices • Digital camera • Video camera • Audio input device • i-Phone • ...

32. 7. Output Unit • Output hardware consists of external devices that transfer information from the computer's CPU to the computer user. • Hard copy • Output that has been recorded in a permanent form onto a medium such as paper. • Soft copy • Generally refers to display output, which appears only temporarily.

33. Display Devices • A display device is the most common form of output device. It is used to display output on a computer screen; for PCs, this device is usually called a monitor. • Cathode ray tube (CRT) • Flat-panel screen • Features of display devices • Size • Resolution • Graphics standards • Video graphics array • VGA (640*480*16), SVGA (800*600*16), XGA (1024*768*256) • Color vs. monochrome display

34. Printers • Characteristics of printers • Print resolution • Dots per inch (DPI) • Impact printing • Dot-matrix printers • ... • Nonimpact printing • Laser printers • Ink-jet printers • ...

35. Multimedia Output Devices • Speakers • Data and multimedia projectors • Multifunction devices

36. 8. Strategies for Making Computer Speedier • Moving circuits close together: 0.13 -> 0.09 µm • Increasing register size: 32 -> 64 bits • Faster and wider buses: 800 MHz FSB • Improved materials for IC • Improved instruction set design: • CISC: complex instruction set computing • RISC: reduced instruction set computing • Pipelining and superscalar processing • Multiprocessing and parallel processing

37. Future Trends • Ultrafast science • Nanoscale technology • Biotechnology • Advance robotics • Accelerated computing • Pervasive connectivity