Computer Architecture CH1 Introduction 2019-2020 PDF

Computer Architecture CH1 Introduction BY DR. Hani Amasha 2019-2020  2 Textbooks 1- Computer Organization and Architecture: Designing for Performance, 8th Edition By William Stallings,...

Computer Architecture CH1 Introduction BY DR. Hani Amasha 2019-2020  2 Textbooks 1- Computer Organization and Architecture: Designing for Performance, 8th Edition By William Stallings, PrenticeHall 2- Mano-M-M-computer-system-architecture: Computer Organization & Architecture - COA 8 The task that the computer designer handles is a complex one : Determine what are important for a new machine, then design a machine to maximize performance while staying within cost constraints This task has many aspects, including: instruction set design, functional organization, logic design, and implementation.  Computer architecture Computer organization Refers to those parameters of a Refers to the operational units9 and computer system that are visible to a their interconnections that realize the programmer or those parameters that architectural specifications. have a direct impact on the logical Examples of organizational attributes execution of a program. Examples of include those: architectural attributes include hardware details transparent to the the instruction set , programmer, such as control signals , interfaces between the computer the number of bits used to represent and peripherals , different data types, the memory technology used. I/O mechanisms, and techniques for addressing memory. e.g. Is there a hardware multiply unit or is it done by repeated addition? e.g. Is there a multiply instruction? Is  Architectural Differences Length of microprocessors’ data word 4, 8, 16, 32, 64, & 128 bit Speed of instruction execution Clock rate & processor speed Size of direct addressable memory CPU architecture Instruction set Number & types of registers Support circuits Compatibility with existing software & hardware development systems So the design is not unique , but depends on the choice of the above points64  Computer architecture 13 There are two types of architecture: Von Neumann Architecture & Harvard Architecture Von Neumann Architecture 1 It is named after the mathematician and early computer scientist John Von Neumann. 2 The computer has single storage system(memory) for storing data as well as program to be executed. 3 A single set of address/data buses between CPU and memory. Harvard Architecture 1The name is originated from "Harvard Mark " a relay based old computer,which stored instruction on punched tape(24 bits wide) and data in electo-mechanical counters. 2 The computer has two separate memories for storing data and program. 3 Two sets of address/data buses between CPU and memory. & Harvard ArchitectureVon Neumann 14  Structure & Function 19 Structure is the way in which components relate to each other Function is the operation of individual components as part of the structure. Computer Functions ❖ Data processing ❖ Data storage ❖ Data movement ❖ Control  20 Data movement Data Storage  21 Processing from/to storage Processing from storage to I/O  What is a computer? 22 Simply, a computer is a sophisticated electronic calculating machine that::  Accepts information to be processed as input.  Stores a list of instructions to process the information.  Processes the information according to the list of instructions.  Provides the results of the processing as output.  Information in a computer - Instructions 23 Instructions specify commands to:  Transfer information within a computer (e.g., from memory to ALU)  Transfer of information between the computer and I/O devices (e.g., from keyboard to computer, or computer to printer)  Perform arithmetic and logic operations (e.g., Add two numbers, Perform a logical AND). A sequence of instructions to perform a task is called a program, which is stored in the memory. Processor fetches instructions that make up a program from the memory and performs the operations stated in those instructions. What do the instructions operate upon?  Information in a computer - Data 24 Data are the “operands” upon which instructions operate. Data could be:  Numbers,  Encodedcharacters. Data, in a broad sense means any digital information. Computers use data that is encoded as a string of binary digits called bits.  A. Central Processor Unit [CPU]: 26 Central processor unit consists of two basic blocks: The program control unit has a set of registers and control circuit to generate control signals. The execution unit or data processing unit contains a set of registers for storing data and an Arithmatic and Logic Unit (ALU) for execution of arithmatic and logical operations. In addition, CPU may have some additional registers for temporary storage of data.  B. Input unit 27 With the help of input unit data from outside can be supplied to the computer. Program or data is read into main storage from input device or secondary storage under the control of CPU input instruction. Example of input devices: Keyboard, Mouse, Hard disk, Floppy disk, CD-ROM drive etc. Binary information must be presented to a computer in a specific format. This task is performed by the input unit: Real world Memory - Interfaces with input devices. - Accepts binary information from Input Unit the input devices. - Presents this binary information in a Processor format expected by the computer. - Transfers this information to the memory or processor.  Output Unit: With the help of output unit computer results can be provided to the user or it can be stored in stograge device permanently for future use. Output data from main storage go to output device under the control of CPU output instructions. Example of output devices: Printer, Monitor, Plotter, Hard Disk, Floppy Disk etc. Computers represent information in a Computer Real world specific binary form. Output units: - Interface with output devices. Memory - Accept processed results provided by the computer in specific binary form. Printer Graphics - Convert the information in binary form to Output Unit display a form understood by an output device. Speakers Processor ……  Memory Unit: 29 Memory unit is used to store the data and program. CPU can work with the information stored in memory unit. This memory unit is termed as primary memory or main memory module. These are basically semi conductor memories. There are two types of semiconductor memories– Volatile Memory : RAM (Random Access Memory). Non-Volatile Memory : ROM (Read only Memory), PROM (Programmable ROM , EPROM (Erasable PROM), EEPROM (Electrically Erasable PROM).  Memory unit 31  Memory unit stores instructions and data.  Recall, data is represented as a series of bits, so , memory unit thus stores bits.  Processor reads instructions and reads/writes data from/to the memory during the execution of a program.  In theory, instructions and data could be fetched one bit at a time.  In practice, a group of bits is fetched at a time.  Group of bits stored or retrieved at a time is termed as “word”  Number of bits in a word is termed as the “word length” of a computer.  In order to read/write to and from memory, a processor should know where to look::  “Address” is associated with each word location.  Processor reads/writes to/from memory based on the memory address:  Access any word location in a short and fixed amount of time 32 based on the address.  Memory provides fixed access time independent of the location of the word. Access time is known as “Memory Access Time”.  Memory and processor have to “communicate” with each other in order to read/write information.  In order to reduce “communication time”, a small amount of RAM (known as Cache) is tightly coupled with the processor.  Modern computers have three to four levels of RAM units with different speeds and sizes:  Fastest, smallest known as Cache  Slowest, largest known as Main memory.  Big-Endian and Little-EndianAssignments 37 Big-Endian: lower byte addresses are used for the most significant bytes of the word. Little-Endian: opposite ordering, lower byte addresses are used for the less significant bytes of the word