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Fundamental of Operating Systems Chuong Huynh May 21, 2001 National Center for Biotechnology Information, National Library of Medicine, National Institute of Health http://www.dbbm.fiocruz.br/class/ Computer Terminology • Hardware – the part of the system you can hit with a hammer (I.e. the physical aspect of computers, telecommunications, and other information technology devices) [includescables, connectors, power supply, peripheral devices) • Software – Program instructions that you can only curse at (I.e. the various kinds of programs used to operate computers and related devices • Middleware – programs that mediate between application and system software or between two different application software • Firmware (microcode) – programming that is loaded in a More on Unix utilities special area of microprocessor or read-only memory on a one time or infrequenet basis so that it is seems to be part of the OS. • Utility – small useful programs with limited capability sometimes comes with the operating system but can be used independent of the OS. Computer Terminology - Hardware • Motherboard? – Motherboard is the main controller board inside the commputer that everything else is attaches to • Microprocessor – computer “brain” also called central processing unit • Memory (RAM) chips – provide the working memory for your software (data not persistent) Computer Terminology - Hardware • ROM (read only memory) – ROM chips control your computer, e.g. the Basic Input/Output System (BIOS). Contain instructions that tells microprocesor how to deal with input and output. • Hard disk and floppy disk drives – more permanent storage of data ( • Expansion cards and slots ( add additional features via PCI and ISA slots) Computer Terminology - Bus • Information travels within your PC on thin metal conductors called bus. The CPU uses the bus to shuttle information between parts of your PC. The faster the bus he faster the PC can work. • Types of bus in a PC: – Address bus: identifiies which memory location will be used next – Control bus: carries signals from the control unit makes sure the bus traffic goes smoothly – Data bus: transfer data to and from microprocessor and memory. • dcar Computer terminology – Power supply • Power supply: start hard drive; provide safe stable current to the motherboard • Electrical problems: – Voltage spikes: short duration surges in the power line. (a billionth of a second) (common) – Power surges: longer version of the spike (last milliseconds) – Brownouts (power sag): occurs when voltage occurs when line voltage falls below required by computers and other equipment – Blackout: complete interruption of powe • UPS (Uninteruptable Power Supply) and surge protectors which protects again voltage spikes Software + Hardware Working Together • User input information from an input device (like a keyboard), electrical impulses are generated. The microprocessor (CPU) translates and temporarily stores these impulses in its electronic memory (RAM). • Software also stored temporarily in RAM, translates these impulses appropriately according to the task or command you’ve entered. • Information is sent by the CPU to the monitor (output) so you can see the progress. • Change document stored in temporary memory. • Finished editing the document, save it permanently to a magnetic disk (hard drive or floppy drive). • When you want to work on the document you load document into RAM from disk. Do we need an operating system? • Does a microwave oven have an operating system? NO, not all computers have operating systems. The more complex ones do. How Operating Systems Work – short ver • An operating system (OS) is a program that after being initially loaded into the computer by a boot program manages all the other programs in a computer. The other programs are the “applications”. The application program uses the OS by making requests for services through a defined application program interface (API). • User interact with the OS via a user interface, e.g. a command line or a graphical user interface (GUI) Operating System Does … • It manages the hardware and software resources of the computer system. These resources include things such as the processor, memory, disk space, etc. • It provides a stable, consistent way for applications to deal with the hardware without having to know all the details of the hardware Operating Systems Also Does • In a multitasking operating system where multiple programs can be running at the same time, the operating system determines which applications should run in what order and how much time should be allowed for each application before giving another application a turn. • It manages the sharing of internal memory among multiple applications. • It handles input and output to and from attached hardware devices, such as hard disks, printers, and dialup ports. • It sends messages to each application or interactive user (or to a system operator) about the status of operation and any errors that may have occurred. • It can offload the management of what are called batch jobs (for example, printing) so that the initiating application is freed from this work. • On computers that can provide parallel processing, an operating system can manage how to divide the program so that it runs on more than one processor at a time. How OS Works – Detail Version (1) • Power on run instructions in ROM examine system hardware for proper functionality • Power on Self Test (POST) checks the CPU, memory, and the BIOS for errors and stores the result in a special memory location • POST successful software loaded in ROM (firmware) begin to activate computer disk drives • The computer activates the hard drives and finds the first piece of the OS, the bootstrap loader which loads the OS into memory, sets up small driver programs (interface with hardware subsystems on computer). • OS has control of the computer now. How OS Works – Detailed Version (2) • Processor management (process or thread) • Memory management • Device management • Storage management • Application management • User interface Core of all operating Systems, but some OS Have additional functionality e.g via built-in utilities Processor Management • OS schedule work done by the processor as either a process or a thread. • A process is software that performs some action and can be controlled by a user, by other applications or by the operating system. • In multitasking system: OS arrange execution of applications so you believe several things are happening at once. Memory and Storage Management OS needs to accomplish • Each process must have enough memory to execute and it can neither run into the memory space of another process nor be run into by another process (memory boundaries for types of software and for individual applications • Next the different types of memory in the system must be used properly so that each process can run effectively.: Device Management • The path between OS and all hardware not on the motherboard goes through a special program called a driver • Driver acts as a translator between electrical signals of the hardware sub systems and high level programming languages of OS and application programs. Application Interface • Application Programming Interfaces (API’s) let application programmers use functions of the computer and OS without having to directly keep track of all details in the CPU’s operation. – simplify matters. • User interface provides a consistent way for a user to interact with a computer, e.g. a graphical user interfacek • Unix user interface is via a shell allow it easier to use and manipulate the operating system (bash, Korn shell, C Shell) and graphical user interface like Konqueror, gnome, Unix SUKH SHELL Utility Kernel Hardware Operating Systems For Bioinformatics • Apple Macintosh: ease of use, popular to educators; Disadvantage: Traditionally, NO COMMAND LINE INTERFACE; Mac OS X (but currently really not many software available) MacVector Single User MultiTasking• Microsoft Windows: most common desktop environment; software available • IBM OS/2 Warp: • BeOS: too new no established software • SGI IRIX: MultiUser • Sun Solaris: MultiUser • Linux (various flavors): • BSD (Berkeley What are the Single User MultiTasking choices? alot –> http://www2.tunes.org/Review/OSes.html