CS11 Digital Logic and Organization

1. University of the Sulaimani (UOS).Faculty of Science and Sciences Education School of ScienceDepartment of Computer CS11 Digital Logic and Organization Lecture 3: Basic Computer Operation (Input, Storage, Processing, Output, and Control) RebazNawzad

2. Basic Computer Operation (Input, Storage, Processing, and Output)

3. Basic Computer Operation Block diagram of Computer Organisation

4. 1. Input • Input: this is the process of entering data and programs into the computer system. • Input devices accept data and instructions from the user. Following are the examples of various input devices, which are connected to the computer for this purpose. • 1. Keyboard • 2. Mouse • 3. Light Pen • 4. Optical/magnetic Scanner • 5. Touch Screen • 6. Microphone for voice as input • 7. Track Ball

5. Input Devices • Electronic Circuits • Most expensive of the three forms for storing binary information. • A flip-flop circuit has either one electronic status or the other. It is said to flip-flop from one to the other. • Electronic circuits come in two forms: • Permanent • Non-permanent • Magnetic Technology • Two parts to most of the magnetic forms of information storage: • The medium that stores the magnetic information. • Example: Floppy disk. Tiny spots on the disk are magnetized to represent 0s and 1s. • The device that can “read” that information from the medium. • The drive spins the disk. • It has a magnetic sensing arm that moves over the disk. • Performs nondestructive reading. • Optical • Uses lasers to “read” the binary information from the medium, usually a disc. • Millions of tiny holes are “burned” into the surface of the disc. • The holes are interpreted as 1s. The absence of holes are interpreted as 0s.

6. 2. Output • Output: This is the process of producing results from the data for getting useful information. • Output devices return processed data that is information, back to the user. Some of the commonly used output devices are: • 1. Monitor (Visual Display Unit): CRT, LCD, LED • 2. Printers • 3. Plotter • 4. Speakers

7. 3. Memory Units: • Volatile Memory: Volatile memory is computer memory that requires power to maintain the stored information. Most modern semiconductor volatile memory is either Static RAM (see SRAM) or dynamic RAM (see DRAM). • Non-Volatile Memory: Non-volatile memory is computer memory that can retain the stored information even when not powered. Examples of non-volatile memory include read-only memory (see ROM), flash memory, most types of magnetic computer storage devices (e.g. hard disks, floppy discs and magnetic tape), optical discs, and early computer storage methods such as paper tape and punched cards.

8. 3. Storage: Memory Unit: Computer is used to store data and instructions. • Primary storage, which holds data in memory (sometimes called random access memory or RAM) and other "built-in" devices such as RAM, primary storage includes read-only memory (ROM) and L1 and L2 cache memory. • Secondary storage, which holds data on hard disks, tapes, and other devices requiring input/output operations. • Tertiary storage, provides a third level of storage. Typically it involves a robotic mechanism which will mount (insert) and dismount removable mass storage media into a storage device according to the system's demands; these data are often copied to secondary storage before use. It is primarily used for archiving rarely accessed information since it is much slower than secondary storage  • Off- line storage, is a computer data storage on a medium or a device that is not under the control of a processing unit.

9. 4. Control Unit • Control Unit (CU): will manage the process of moving data and program into and out of memory and also deal with carrying out (executing) program instruction – one at the time. This include the idea of “register” to hold intermediate values. In the illustration above, the “accumulator” is one such as register • Control Unit (CU): The process of input, output, processing and storage is performed under the supervision of a unit called 'Control Unit'. It decides when to start receiving data, when to stop it, where to store data, etc. It takes care of step-by-step processing of all operations in side the computer. • Coordinates and controls all parts of the computer system

10. 5. Arithmetic Logic Unit (ALU): • The major operations performed by the ALU are addition, subtraction, multiplication, division, logic and comparison. • Performs arithmetic or logical operations

11. Von Neumann Computer Consists of five basic elements: • (input, memory, control unit, arithmetic logic unit ALU and output) • The control unit read or obtains an instruction from memory and decode or translate it. • For arithmetic or logic-type instruction, the control unit generates enable signals for the ALU to perform the required operation. • For input/output (I/0) instruction, the control unit generates enable signals for (I/0) either to input data from or output data to external devices.

12. Von Neumann Architecture Input Output Memory Control CONTROL ALU INSTRUCTION

13. http://upload.wikimedia.org/wikipedia/commons/8/84/Von_Neumann_architecture.svghttp://upload.wikimedia.org/wikipedia/commons/8/84/Von_Neumann_architecture.svg

14. Ether-net SCSI USB Modem Soundcard Printer Mouse Key-board Hardware Organization (typical Pentium): homework? Main Memory AGP Port Level 2 cache CPU Bridge Graphics card Moni-tor ISA bridge PCI bus IDE disk ISA bus

15. Computers Use Random Access Technology - Data Can Be Accessed in Any Order at Any Time Regardless of Storage Position or Time of Creation.

17. The Language of Computers • Binary: the digital language of computers. This language is composed of an alphabet containing only 2 “letters” known as bits. Any work done on a modern computer from word processing to digital audio is translated to this language.

18. Digital Letters and Words • Bit: the smallest form of information in the language of computers. It is represented as a zero or a one. A bit can be considered a letter in the digital language of binary. • Byte: a “word” of information in binary. It is made of a number bits determined by the bit rate. 8 bits is usually = 1 byte on modern computers.

19. Bit Rate • Bit rate: the number of “letters” or bits in a digital word or byte. An example of a 16 bit digital word in binary could be (01010101 10101010).

20. Example • 8 bits = 1 byte • 1024 bytes = 1 kilobyte (210) • 1024 kilobytes = 1 megabyte (220) • 1024 megabytes = 1 gigabyte (230)

21. Important Hardware(CPU ) • CPU - abbreviation of central processing unit, the CPU is the brains of the computer. Sometimes referred to simply as the processor or central processor, the CPU is where most calculations take place. In terms of computing power, the CPU is the most important element of a computer system.

22. Clock Speed • Clock speed - also called clock rate, the speed at which a microprocessor executes instructions. Every computer contains an internal clock that regulates the rate at which instructions are executed and synchronizes all the various computer components. The faster the clock, the more instructions the CPU can execute per second.

23. Bus • A bus is a collection of wires through which data is transmitted from one part of a computer to another. You can think of a bus as a highway on which data travels within a computer. There are various types of busses, both internal and external, that connect the hardware, inside and outside, the computer. • Like the CPU, busses have a clock speed. A fast bus allows data to be transferred faster, which makes applications run faster.

24. HARD DISK (Storage Device) • The hard disk is a magnetic disk on which you can store computer data. The term hard is used to distinguish it from a soft, or floppy, disk. Hard disks hold more data and are faster than floppy disks. A hard disk, for example, can store anywhere from 10 to more than 100 gigabytes, whereas most floppies have a maximum storage capacity of 1.4 megabytes.

25. RAM Vs. ROM (Memory) • Is an acronym for random access memory, a type of computer memory that can be accessed randomly; That is, any byte of memory can be accessed without touching the preceding bytes. RAM is the most common type of memory found in computers and other devices, such as printers.

26. RAM Vs. ROM • In common usage, the term RAM is synonymous with main memory, the memory available to programs. For example, a computer with 300M RAM has approximately 2400 million bytes of memory that programs can use. In contrast, ROM (read-only memory) refers to special memory used to store programs that boot the computer and perform diagnostics. In fact, both types of memory (ROM and RAM) allow random access. To be precise, therefore, RAM should be referred to as read/write RAM and ROM as read-onlyRAM.

27. Peripherals • Operating systems perform basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices.

28. PERIPHERALS

29. Functional Units (Arithmetic and Logic Unit, Control Unit, Central Processing Unit)

30. The Central Processing Unit (CPU) The Central Processing Unit is a silicon chip that is the ‘brain’ of a computer system.It executes program instructions and data and controls all the devices within the machine It’s internal organisation (architecture) consists of 3 main parts: • Control unit (CU) • Arithmetic and Logic unit (ALU) • Registers The CPU

31. Address bus Memory Address Register Other registers Data bus Memory Data Register Main Memory Control Bus (Read / Write) Arithmetic and Logic Unit (ALU) Control Unit Clock pulses Electronic clock Inside the CPU The CPU

32. The Control Unit The CU in the processor controls all other parts of the processor and makes sure that the program instructions of the computer are carried out in the correct place at the correct time. It manages fetch, decode and execute program instructions. It synchronises the whole system by telling devices what to do and when to do it The CPU

33. The Arithmetic and Logic Unit The ALU is where data is actually processed in the CPU Processing data in the ALU involves doing arithmetic calculations e.g. add, subtract, multiply, divide etc. It also involves logical comparisons like AND, OR etc. using electronic circuitry The CPU

34. The Registers The Registers are groups of storage locations inside the processor itself. There are many registers including: • Memory Address Register (MAR) – holds the address of a location in memory • Memory Data Register (MDR) – holds data just read from or written to memory • Program Counter (PC) – holds the address of the next instruction to be fetched • Instruction Register (IR) – holds the current instruction being executed The precise details of each register and how they function is not required at Higher level The CPU

35. Questions • Why is a computer known as a two state machine? • A processor has three main parts name each of them. • What is a storage location? • How is the processor connected to the main memory? The CPU

36. Answers • It is a two state machine as all data is stored as 1 or 0’s in machine code. • Registers, Arithmetic and Logic Unit and Control Unit make up the CPU • Registers are temporary storage locations for data, instructions or addresses • The processor is connected to the main memory by various wires called buses The CPU

37. Functional Units Block diagram of Computer Organisation

38. Central Processing Unit • The part of the computer performs the bulk of data processing operations is called the central processing unit • The CPU is made up of three major parts: • Register set • ALU • Control units

39. Central Processing Unit = “brain” • Executes programs by: • Fetching and decoding the next instruction from memory • Execute it • Consists of: • Control Unit • Arithmetic Logic Unit (ALU) • Registers (high-speed memory) • Program Counter (PC) • Instruction Register (IR) Control Unit Arithmetic Logic Unit I/O Devices Main Memory Disk Printer Registers Bus

40. CPU The central processing unit (CPU) of a computer is the main unit that dictates the rest of the computer organization • 1. Register set: Stores intermediate data during the execution of instructions; • 2. Arithmetic logic unit (ALU): Performs the required micro-operations for executing the instructions; • 3. Control unit: supervises the transfer of information among the registers and instructs the ALU as to which operation to perform by generating control signals. Control Unit Arithmetic Logic Unit Registers

41. Processing Processing Control Unit ALU Register

42. 1: Control Unit (CU): • Control Unit (CU): The process of input, output, processing and storage is performed under the supervision of a unit called 'Control Unit'. It decides when to start receiving data, when to stop it, where to store data, etc. It takes care of step-by-step processing of all operations in side the computer. • Coordinates and controls all parts of the computer system

43. 2 Arithmetic Logic Unit (ALU): • The major operations performed by the ALU are addition, subtraction, multiplication, division, logic and comparison. • Performs arithmetic or logical operations

44. 3 Register • Stores the most frequently used instructions and data

45. Components of the CPU? • Control unit- Coordinates and controls all parts of the computer system • Arithmetic-Logic unit- Performs arithmetic or logical operations • Registers-Stores the most frequently used instructions and data.

46. How CPUs work? Fetch- Gets next program instruction from the computer’s memory Decode- Figure out what the program is telling the computer to do Execute- Perform the requested action Write-back (Store)- Write (store) the results to a register or to memory Arithmetic-Logic Unit (ALU)- Perform Basic Arithmetic or logic operations: Add, Subtract, Multiply, Divide Compare two items to see which one is larger or smaller Register: It has some of the memory functionality.