Computer Organization and Architecture: An Overview Lecture PDF

COMPUTER ORGANIZATION AND ARCHITECTURE: AN OVERVIEW  MODULE 1  Overview  The main components of a computer  Computer structure and functions  Computer Level Hierarchy  An Example System  Overview: Computer Types  Computers can be generally classified by size and p...

COMPUTER ORGANIZATION AND ARCHITECTURE: AN OVERVIEW  MODULE 1  Overview  The main components of a computer  Computer structure and functions  Computer Level Hierarchy  An Example System  Overview: Computer Types  Computers can be generally classified by size and power as follows, though there is considerable overlap:  Personal computer: A small, single-user computer based on a microprocessor.  Workstation: A powerful, single-user computer. A workstation is like a personal computer, but it has a more powerful microprocessor and, in general, a higher-quality monitor.  Minicomputer: A multi-user computer capable of supporting up to hundreds of users simultaneously.  Mainframe: A powerful multi-user computer capable of supporting many hundreds or thousands of users simultaneously.  Supercomputer: An extremely fast computer that can perform hundreds of millions of instructions per second.  Mobile Devices (like smartphones, PDAs etc)  Computers : Definition  An electronic device for storing and processing data, typically in binary form, according to instructions given to it in a variable program.  An electronic device designed to accept data, perform prescribed mathematical and logical operations at high speed, and display the results of these operations Keywords: store, process, input and output Computer Components in Detail  Computer Architecture Computer Organization Attributes of a system Instruction set, number of visible to the bits used to represent programmer various data types, I/O Have a direct impact on mechanisms, techniques the logical execution of a for addressing memory program Architectural Computer attributes Architecture include: Organizational Computer attributes Organization include: Hardware details The operational units and transparent to the their interconnections programmer, control that realize the signals, interfaces architectural between the computer specifications and peripherals, memory technology used © 2016 Pearson Education, Inc., Hoboken, NJ. All rights reserved.  Comp. Organization vs Comp. Architecture Computer Organization Computer Architecture  Refers to the how features  Focuses on the structure and are implemented  how the behaviour of computer computer is controlled systems  The physical aspects of a  The logical aspect of system computer system implementation (as seen by the programmer) Control signals The instruction set Interfaces between The number of bits used computer and peripherals Data types I/O mechanisms The memory technology / memory types used memory addressing techniques 8 Embedded Sys. Fundamentals Spring 17 © Ahmad El-Banna  The computer family  Many computer manufacturers offer a family of computer models, all with the same architecture but with differences in organization.  All Intel x86 family share the same basic architecture  The IBM System/370 architecture first introduced in 1970 included a number of models that share the same basic architecture and has survived to this day as the architecture of IBM’s mainframe product line.  The newer models retained the same architecture so that the customer’s software investment was protected (code compatibility)  Computers: Structure and Function  A computer is a complex system with a hierarchical system of interrelated subsystems with different levels.  At each level, the designer is concerned with structure and function:  Structure: The way in which the components are interrelated.  Function: The operation of each individual component as part of the structure.  COMPUTER I/O Main memory System Bus CPU CPU Registers ALU Structure Internal Bus Control Unit CONTROL UNIT Sequencing Logic Control Unit Registers and Decoders Control Memory Figure 1.1 A Top-Down View of a Computer © 2016 Pearson Education, Inc., Hoboken, NJ. All rights reserved.  Computer: 4 main structural components Computer Central Main I/O System processing memory interconnection unit (CPU) Moves data Stores data between the Controls the computer and Mechanism for operation of its external communication the computer environment among CPU, and performs main memory, its data and I/O processing functions  Structure: CPU CPU Arithmetic and CPU Control Unit Registers logic unit Interconnection (ALU) Controls CPU Mechanism for operations Provides storage communication Performs the internal to the computer’s data among the CPU control unit, processing functions ALU, and registers  FUNCTION Functions There are only four functions process data in variety of forms and Data Processing requirements short and long term data storage for retrieval Data storage and update move data between computer and outside Data movement world. Control control of process, move and store data using instruction. Functions are performed through programs  Program  A sequence of steps  For each step, a computer function is executed  For each operation, a different/new set of control signals is needed  For each operation a unique code (instruction) is provided  e.g. ADD, MOVE  A hardware segment accepts the code and issues the control signals  Program: Execution Approach 1: Hardwired Approach 2: Software Built into (wired Control signals into) computers through hardware instruction codes Uses a sequence of Needs an arithmetic and interpreter to logic functions “speak machine” Provides high speed While less speed, but inflexible to it is easily change reprogrammable Program: Execution 12 Embedded Sys. Fundamentals Spring 17 © Ahmad El-Banna  The Computer Level Hierarchy  Computers consist of many things besides chips.  Before a computer can do anything worthwhile, it must also use software.  Writing complex programs requires a “divide and conquer” approach, where each program module solves a smaller problem.  Complex computer systems employ a similar technique through a series of virtual machine layers.  The Computer Level Hierarchy  Each virtual machine layer is an abstraction of the level below it.  The machines at each level execute their own particular instructions, calling upon machines at lower levels to perform tasks as required.  Computer circuits ultimately carry out the work.  The Computer Level Hierarchy  Level 6: The User Level  Program execution and user interface level.  The level with which we are most familiar.  Level 5: High-Level Language Level  The level with which we interact when we write programs in languages such as C, C++, Pascal, Lisp, and Java.  The Computer Level Hierarchy  Level 4: Assembly Language Level  Acts upon assembly language produced from Level 5, as well as instructions programmed directly at this level.  Level 3: System Software Level  Controls executing processes on the system.  Protects system resources.  Assembly language instructions often pass through Level 3 without modification.  The Computer Level Hierarchy  Level 2: Machine Level  Alsoknown as the Instruction Set Architecture (ISA) Level.  Consists of instructions that are particular to the architecture of the machine.  Programs written in machine language need no compilers, interpreters, or assemblers.  The Computer Level Hierarchy  Level 1: Control Level A control unit decodes and executes instructions and moves data through the system.  Control units can be microprogrammed or hardwired.  A microprogram is a program written in a low-level language that is implemented by the hardware.  Hardwired control units consist of hardware that directly executes machine instructions.  The Computer Level Hierarchy  Level 0: Digital Logic Level  This level is where we find digital circuits (the chips).  Digital circuits consist of gates and wires.  These components implement the mathematical logic of all other levels.  An Example system Consider this advertisement: What does it all mean?? 41  An Example System Measures of capacity and speed: Kilo- (K) = 1 thousand = 103 and 210 Mega- (M) = 1 million = 106 and 220 Giga- (G) = 1 billion = 109 and 230 Tera- (T) = 1 trillion = 1012 and 240 Peta- (P) = 1 quadrillion = 1015 and 250 Exa- (E) = 1 quintillion = 1018 and 260 Zetta- (Z) = 1 sextillion = 1021 and 270 Yotta- (Y) = 1 septillion = 1024 and 280 Whether a metric refers to a power of ten or a power of two typically depends upon what is being measured.  An Example System  Hertz = clock cycles per second (frequency)  1MHz = 1,000,000Hz  Processor speeds are measured in MHz or GHz.  Byte = a unit of storage  1KB = 210 = 1024 Bytes  1MB = 2 = 1,048,576 Bytes 20  Main memory (RAM) is measured in MB or GB  Disk storage is measured in GB for small systems, TB for large systems.  An Example System Measures of time and space: Milli- (m) = 1 thousandth = 10 -3 Micro- () = 1 millionth = 10 -6 Nano- (n) = 1 billionth = 10 -9 Pico- (p) = 1 trillionth = 10 -12 Femto- (f) = 1 quadrillionth = 10 -15 Atto- (a) = 1 quintillionth = 10 -18 Zepto- (z) = 1 sextillionth = 10 -21 Yocto- (y) = 1 septillionth = 10 -24  An Example System  Millisecond = 1 thousandth of a second  Hard disk drive access times are often 10 to 20 milliseconds.  Nanosecond = 1 billionth of a second  Main memory access times are often 50 to 70 nanoseconds.  Micron (micrometer) = 1 millionth of a meter  Circuits on computer chips are measured in microns.  An Example System  We note that cycle time is the reciprocal of clock frequency.  A bus operating at 133MHz has a cycle time of 7.52 nanoseconds: 133,000,000 cycles/second = 7.52ns/cycle Now back to the advertisement...  An Example System The microprocessor is the “brain” of the system. It executes program instructions. This one is a Pentium (Intel) running at 4.20GHz. A system bus moves data within the computer. The faster the bus the better. This one runs at 400MHz.  An Example System Computers with large main memory capacity can run larger programs with greater speed than computers having small memories. RAM is an acronym for random access memory. Random access means that memory contents can be accessed directly if you know its location. Cache is a type of temporary memory that can be accessed faster than RAM.  An Example System This system has 256MB of (fast) synchronous dynamic RAM (SDRAM)... … and two levels of cache memory, the level 1 (L1) cache is smaller and (probably) faster than the L2 cache. Note that these cache sizes are measured in KB.  An Example System Hard disk capacity determines the amount of data and size of programs you can store. This one can store 80GB. 7200 RPM is the rotational speed of the disk. Generally, the faster a disk rotates, the faster it can deliver data to RAM. (There are many other factors involved.)  An Example System ATA stands for advanced technology attachment, which describes how the hard disk interfaces with (or connects to) other system components. A CD can store about 650MB of data. This drive supports rewritable CDs, CD-RW, that can be written to many times.. 48x describes its speed.  An Example System Ports allow movement of data between a system and its external devices. This system has ten ports.  An Example System Serial ports send data as a series of pulses along one or two data lines. Parallel ports send data as a single pulse along at least eight data lines. USB, Universal Serial Bus, is an intelligent serial interface that is self-configuring. (It supports “plug and play.”)  An Example System System buses can be augmented by dedicated I/O buses. PCI, peripheral component interface, is one such bus. This system has three PCI devices: a video card, a sound card, and a data/fax modem.  An Example System 55 The number of times per second that the image on a monitor is repainted is its refresh rate. The dot pitch of a monitor tells us how clear the image is. This one has a dot pitch of 0.24mm and a refresh rate of 75Hz. The video card contains memory and programs that support the monitor.  Conclusion  This chapter has given you an overview of the subject of computer architecture.  You should now be sufficiently familiar with general system structure to guide your studies throughout the remainder of this course.  Subsequent chapters will explore many of these topics in great detail.