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Digital Electronics and File Management Unit D 1 Objectives Introduce Digital Data Representation Introduce Integrated Circuits Explore Processor Performance Factors Understand Computer Memory: RAM Explore Computer Memory 2 Objectives Introduce Computer File Basics Understand File Locations Explore File Management Understand Logical File Storage Use Files Understand Physical File Storage 3 Digital Data Representation The form in which information is conceived, manipulated and recorded on a digital device. Uses discrete digits/electronic signals Byte = 8 bits = 1 character 4 Numeric Data Consists of numbers representing quantities used in arithmetic operations. – Binary system, “Base 2” - 1,0 (bits - binary digits) - On/Off, Yes/No 5 Coding Systems Depends on computer File headers ASCII (7 bits) Extended ASCII (8 bits current PCs) EBCIDIC (8 bits - older IBM machines ) Unicode (16 bits - good for languages - future) 6 Quantifying Bytes and Bits Bit = b Nibble = Half of a byte Byte = B Kilobyte (KB) (1024 bytes) Megabyte (MB) (Million bytes) Gigabyte (GB) (Billion bytes) Terabyte (TB) (Trillion bytes) 7 Integrated Circuits A super thin slice of semi–conducting material packed with microscopic circuit elements such as wires, transistors, capacitors, logic gates, and resistors. Bits are represented as electrical pulses that travel over these circuits. Also called a chip, microchip and computer chip. 8 Integrated Circuits (cont.) Chips are classified by number of components they contain – SSI (small-scale integration), less than 100 components per chip – ULSI (Ultra large-scale) over 1 million Semi conducting materials used to make chips – Silicon and germanium 9 Integrated Circuit Uses processors Memory Support circuitry Chip Package 10 Processor Packages DIPs (dual in-line packages) DIMMs (dual in-line memory modules) PGAs (Pin-grid arrays) SECs (single-edge contact cartridges) 11 Microprocessor (Processor) Designed to process instructions Largest chip on motherboard Intel: world’s largest chipmaker (Pentiums) AMD: Cheaper chips (Athlons) 12 Motherboard Main circuit board 13 Inside the System Unit The system unit of a PC is the case that houses processing hardware and other hardware. All of the hardware contained within the system unit is connected to the system board or motherboard. 14 15 CPU The CPU (central processing unit) does the vast majority of processing for a computer. CPUs contains a variety of circuitry and components and are connected to the motherboard. Also called the processor or microprocessor. 16 CPU, Cont’d. Processing speed (clock speed) is measured in megahertz (MHz) or gigahertz (GHz) and measures the number of clock ticks per second. A computer word is a group of bits or bytes that a CPU can manipulate at one time. Other factors that affect the 17 Memory: RAM RAM (random access memory) is the computer’s main memory and is used to temporarily storage programs and data with which it is working. RAM is volatile (erased when the power to the PC goes off). RAM comes in a variety of types, speeds, and size. Types of RAM include: DRAM SRAM SDRAM DDR SDRAM RDRAM DDR-II SDRAM 18 Memory: Other Types Cache memory—fast memory chips located on or close to the CPU chip (L1, L2, and L3). Registers—high speed memory built into the CPU. ROM (read-only memory)—non- 19 Buses Buses are electronic paths that data travels around on a computer system. Internal buses move data around within the CPU. Expansion buses establish 20 21 Expansion Slots and Cards Expansion for desktop PCs. – Expansion cards can be inserted into expansion slots on the motherboard. – Some external devices can be plugged into existing USB or FireWire ports without adding another expansion card. PC cards—used with notebook PCs. 22 Ports Connectors to which devices can be attached. Serial Common ports: – Keyboard Parallel – Mouse SCSI – Monitor USB FireWire Network – Modem – MIDI – IrDA 23 24 How the CPU Works The CPU is a collection of electronic circuits and components. Impulses from an input device passes through RAM and enters the CPU via a system bus. Within the CPU the impulses move through the circuits and components to create new impulses. Eventually, a set of electronic impulses leaves the CPU for an output device. 25 Typical CPU Components Arithmetic/lo gic unit (ALU) Control unit Prefetch unit Decode unit Internal cache Bus interface unit Registers 26 27 The System Clock and the Machine Cycle The system clock synchronizes the computer’s operations. The machine cycle is the series of operations involved in the execution of a single, machinelevel instruction. – Fetch – Decode – Execute – Store 28 29 Making Computers Faster Now and in the Future Speeding up your system today. – Add more memory. – Perform system maintenance. – Buy a larger or second hard drive. – Upgrade your Internet connection. – Upgrade your video card. – Upgrade your CPU. 30 Processor Components 31 Processor Performance Speed: processor clock set clock speed (MHz or GHz ) Word Size: number of bits the processor can manipulate at one time (32-bit or 64-bit) Cache: high speed memory (kilobytes) 32 Processor Performance Instruction Set Type: – CISC (Complete instruction set computer) – RISC (Reduced instruction set computer) Processing Technique: – Serial – Pipelining – Parallel Look at benchmark testing to compare 33 Memory Types Random Access Memory (RAM) Virtual Memory Read-Only Memory (ROM) CMOS 34 RAM Random Access Memory Temporary (volatile) holding area for data, application software and operating system Expensive chip set Circuitry Less storage than disk Capacitors hold bits Capacity measured in MB (64 - 512 MB) Speed in nanoseconds 35 Makes the most noticeable difference RAM Types SDRAM – Synchronous Dynamic RAM – fast and cheap – DIMMS – Most popular RDRAM – Rambus Dynamic RAM – faster and more expensive – RIMMs AND SO-RIMMs 36 Virtual Memory Disk based Stores parts of programs and data until they are needed by the processor Works with RAM, but is slower 37 ROM Read-Only Memory Permanent on a chip from manufacturer Holds computer start up routine, which are hard-wired instructions – Only way to change is to replace ROM chip ROM BIOS (basic input/output system) 38 CMOS Complementary Metal Oxide Semiconductor Battery powered More permanent than RAM; less permanent than ROM Stores basic computer configuration Must be updated via CMOS setup program when configuration changed 39 Computer Ads Includes: capacity, speed, and type of RAM Also maximum RAM that can be installed Example: 512 MB 400 MHZ SDRAM capacity speed type 40 Computer File Characteristics A collection of data on a storage medium Filename conventions Filename extension .txt .jpg .exe .doc 41 File Locations Device drive letters A: C: D: Directory – Root Directory (C:\) – Subdirectory or folder (C:\Documents) – File specification or Path – File size and date C:\Music\Reggae\Marley One Love.mp3 Drive letter Primary folder Secondary folder Filename Filename extension 42 Deleting Files Move to Recycle Bin in Windows Undelete Empty Bin 43 File Management Helps you organize your computer files File/Save and File/Open Utilities like Windows Explorer or MAC Finder – list, find, move, copy, delete, rename Save vs. Save As 44 Logical File Storage Filing cabinet or tree model Metaphors to help you visualize files on a storage device Windows Explorer Folder hierarchy 45 Using Files Start application (open Word) Create file (type text) Save file (File/Save) Close file and application (File/Exit) Open file again for editing (File/Open) Edit file Save file (with changes, or rename) – File/Save – File/Save As 46 Organizing Files On your computer: – Give files and folders descriptive names – Keep file extensions so files open with correct software – Group similar files into folders – Organize folders from top-down to make retrieval and backup easier 47 Physical File Storage Storage medium formatted into tracks /sectors electronically File system keeps track of names and file locations. – Windows uses FAT32 OR NTFS – Backup your index file Clusters: a group of sectors that speeds up storage and retrieval 48 Physical File Storage FAT (File Allocation Table) on each disk keeps track of where all files are and which clusters are empty. If damaged, you lose everything. Defragmentation Utility rearranges files to be stored in contiguous clusters. 49 Tech talk: How a processor executes instructions Instruction Set is built into processor Instructional Cycle is the execution of a single instruction Fetch Instruction Interpret Instruction Execute Instruction Increment Instruction Pointer 50 Digital Electronics and File Management End 51