BCC Revision Objectives PDF

BCC Revision Time to lock in. Topic 1 Part 2 Third Generation (1960’s – 1970’s) Use integrated circuit (ICs) A single IC has many transistor, resistors and capacitors along with its associated circui...

BCC Revision Time to lock in. Topic 1 Part 2 Third Generation (1960’s – 1970’s) Use integrated circuit (ICs) A single IC has many transistor, resistors and capacitors along with its associated circuitry. Examples: IBM-360 series Honeywell-60000 series PDP (Personal Data Processor) IBM-370/168 TDC-316 Characteristics of Third Generation Computer Operating system : Remote, Time Sharing & Multiprogramming Programming language : FORTRAN II to IV, COBOL, PASCAL, BASIC etc. Features: (as compared to second generation) Smaller size Still costly More reliable Faster Consumed less electricity & generate less heat Fourth Generation (1960’s – 1970’s) Use VLSI (Very Large Scale Integrated) circuit. VLSI circuits has about 5000 transistors and other circuit elements on a single chip, making it possible to have microcomputers of forth generation. Examples ： DEC 10 STAR 10000 PDP 11 CRAY-1 (Super Computer) CRAY-X-MP (Super Computer) Characteristics of Fourth Generation Computer Operating system : Time sharing, real time, networks and distributed processing Programming language : C, C++, DBASE etc. Features: (as compared to third generation) Smaller size Cheaper Portable and reliable Computers became easily available Concept of internet was introduced Topic 2 Part 1  PROCESSORS – CU & A LU Processors contains a Control Unit and an Arithmetic Logic Unit (ALU) that work together to perform processing operations. When a user runs an application, for example, its instruction transfer from a 8 storage device to memory. Data needed by programs and applications enters memory from either an input device or a storage device. The control unit interprets and executes instructions in memory. ALU performs calculations on the data in memory. Result is stored in memory from which it  PROCESSORS – CU & A LU The component of the processor that directs and coordinates most of the operations in the computer. 9 Contr Interprets each instructions issued by a program or ol application and then initiates the appropriate action to carry out the instructions. Unit Type of internal components that the it directs include ALU, registers and buses.  PROCESSORS – CU & A LU Performs arithmetic, comparison and other operations. Arithme Comparison operations include comparing one data 1 tic Logic item with another to determine whether the first item is greater than, equal to or less than the other 0 Unit item. (ALU) Depending on the results of the comparison, different actions may occur. Eg. Compare the number of hours an employee worked during the week with the regular time hours allowed.  S Y S T E M C LO C K The system clock is a small quartz crystal circuit that the processor relies on to control the timing of all computer operations. The system clock generates regular electronic pulses, or ticks that set the operating pace of components in the system unit. 1 Each tick equates to a clock cycle. 1 Processors today are superscalar. Can execute more than one instructions per clock cycle. The faster the clock speed, the more instructions can be executed. Current PC processors have clock speeds in gigahertz. For example, a PC that operates at 3 GHz has 3 billion (giga) clock  M E M O RY The system unit contains TWO types of memory: Volatile Memory Non – Volatile Memory 1 Losses its content when Does not loose content when 2 power is turned off. power is turned off. Memory is temporary. Memory is permanent. Examples: RAM (Random Examples: ROM (Read Only Access Memory) Memory), Flash memory and CMOS  M E M O RY - RA M RAM (random access memory) is also called main memory. Consists of memory chips that can be read from and written to by the processor and other devices. When you turn on power to a computer, certain OS files load into RAM from a storage device such as hard drive. 1 3 These files remain in RAM as long as the computer as the computer has continuous power. As additional applications and data are requested, they also load into RAM from storage. The processor interprets and executes instructions while the program or application is in RAM. RAM can accommodate multiple programs and applications simultaneously.  M E M O RY - RA M Two common types of RAM are dynamic RAM and static RAM: Dynamic RAM (DRAM pronounced DEE-ram) chips must be reenergized constantly or they lose their contents. 1 4  M E M O RY - RA M Static RAM (SRAM pronounced ESS-ram) chips are faster and more reliable than any variation of DRAM chips. These chips do not have to be 1 reenergized as often as DRAM chips, hence the term static. 5 However, it is more expensive than DRAM chips. Special applications such as cache, use SRAM chips. RAM chips usually reside on a memory module, which is a small circuit board. Memory slots on the  M E M O RY C A C H E Memory cache speeds the processes of the computer because it stored frequently used instructions and data. Most PC have memory cache Level 1 (L1) and Level 2 (L2) cache. Some also have Level 3 (L3) cache. 1 L1 cache is built directly on the processor chip. L1 cache usually has a very small capacity. 6 L2 cache is slightly slower than L1 cache but has a much larger capacity. Current processors include advance transfer code (ATC), a type of L2 cache built directly on the processor chip. Processors that use ATC performs at much faster rate. L3 cache is a cache on the motherboard that is separate from the processor chip. When the processor needs an instruction or data, it searches  F L A S H M E M O RY Non-volatile memory that can be erased electronically and rewritten. Most computers use flash memory to hold their start-up instructions because it allows computers to update content easily. 1 7 It also stores data and programs on many mobile devices and peripheral devices, such as smartphones, portable media players, printers, digital cameras, automotive devices and digital voice recorders. When you enter names and addresses in a smartphone, for example, a flash memory chips stores the data. Memory cards contain flash memory on a removable device  BUSES Bits transfer internally within the circuitry of a computer along electrical channels, called buses, which allow for various devices, both inside and 1 attached to the system unit, to communicate with each 8 other. Buses transfer bits from input device to memory, from memory to processor, from the processor to memory and from memory to output or storage devices. Topic 2 Part 2  MICR READER Magnetic Ink Character Recognition (MICR) devices read text printer with magnetized ink. 2 0 An MICR reader converts MICR characters into a form the computer can process. Example: Bank check Topic 2 Part 3  PRINTER Thermal Printer A thermal printer is a printer that makes use of heat in order to produce the image on 2 paper. 2 Thermal printing does not make use of ink or toner unlike many other printing forms but largely depends on thermal papers for producing the images.  PRINTER Dot-Matrix Printer An old technology that produced moderate print quality. 2 The pins on the print head strike 3 against a cloth ink ribbon that comes in direct contact with the paper. Topic 2 Part 4  SEQUENTIAL & DIRECT ACCESS SEQUENTIAL ACCESS DIRECT ACCESS The medium must Find data by deriving read or move through its storage address. 2 all information up to 5 the point it is attempting to read or write to. Example: Tape drive  HARD DISK A hard disk, also called a hard disk drive (HDD) is a storage device that contains one or more inflexible, circular platters that use magnetic particles to store data, instructions, and information. 2 6 Storage capacity of hard disks varies and is determined by: The by the number of platters the hard disk contains The composition of the magnetic coating on the platters (longtinudinal or perpendicular recording). Density – the number of bit in an area on a  HARD DISK 2 7  TAPE A tape is a magnetically coated ribbon of plastic capable of storing large amount of data and 2 information. 8 A tape drive reads and write data information on a tape. Topic 4  NIELSEN’S TEN USABILITY HEURISTICS #3 User control and freedom #4 Consistency and standards Users often choose system functions by Users should not have to wonder whether mistake and will need a clearly marked different words, situations or actions mean “emergency exit” to leave the unwanted the same thing. state without having to go through an extended dialogue. Follow platform conventions. Support undo and redo. https://bit.ly/35XS4sU https://bit.ly/2ZSE8wn Topic 6 Image File Type – PNG (.png) PNG: Portable Network Graphics Compression : Lossless Best for: Web images Designed to improve upon and replaced the gif format. Able to handle up to 16 million colors, unlike the 256 colors supported by GIF. 28 -256 216 – 65k 224 -16 million of colors Image File Type – JPEG (.jpg OR.jpeg) JPEG: Joint Photographic Experts Groups Compression: Lossy Best for: Web images, Non- professional printing, email, PPT The image is compressed to make a smaller file. The compression create non-noticeable loss in quality. Very common on the Internet