2. Computer Hardware and Software

Transcription

1 CSC400 - Operating Systems 2. Computer Hardware and Software J. Sumey Overview Motivation Computer Hardware & Architecture Hardware Support for OS Computer Software CSC400 - Computer Hardware & Software 2 CSC400 - Operating Systems 1

2 Motivation vis: OS provides services and resources to applications that are ultimately tied to the system hardware to properly understand both application and system programming, one must understand computer architecture and I/O device hardware catch 22: "Moore's law" CSC400 - Computer Hardware & Software 3 Computer Hardware & Architecture CSC400 - Operating Systems 2

3 Computer Components modern computers consist of a number of major physical devices configured in a standard architecture mainboard / motherboard processor(s) main / primary memory peripheral & I/O devices CSC400 - Computer Hardware & Software 5 Motherboards printed circuit board (PCB) that physically contains the other hardware components of the computer traces - electrical connections between components on the board bus - collection of traces that form a high-speed communication channel ex: address, data, control; ISA, PCI, AGP chipset - integration of support (glue) logic BIOS - used for bootstrapping (POST) expansion slots - used to plug in add-on cards CSC400 - Computer Hardware & Software 6 CSC400 - Operating Systems 3

4 Clocks the "heartbeat" of the computer operating frequency is produced by clock generator (on motherboard) typically in MHz/GHz instructions are executed in terms of cycles / clockticks t 1 f f = frequency, t = time different clocks at different levels CPU internal, frontside bus (FSB), I/O bus CSC400 - Computer Hardware & Software 7 Processors execute a stream of machine-language instructions for a particular task/app. ex: CPU, coprocessors, DSP have a particular register architecture and instruction set instruction set length typically matches data bus width which directly affects system performance ex: 8, 32, 64 bits CSC400 - Computer Hardware & Software 8 CSC400 - Operating Systems 4

5 Processor Components registers user: Accumulators, PC, SP, SR, index special/control: MAR, MBR, IR instruction fetch & decode units obtains and deciphers instructions controller/sequencer carries out instructions via microcode also controls interrupt processing arithmetic logic unit (ALU) performs data manipulation operations bus interface provide interface to outside world CSC400 - Computer Hardware & Software 9 Memory Hierarchy various levels of memory in the system based on cost & performance differs by access speed, capacity, volatility hierarchy registers cache: L1, L2 measured in terms of latency (wait states) main/physical memory: DRAM, SDRAM, DDR measured in terms of bandwidth secondary memory: disks, Flash, optical, magnetic CSC400 - Computer Hardware & Software 10 CSC400 - Operating Systems 5

6 Peripheral Devices any hardware component not required for a CPU to execute instructions typically are I/O devices that connect to system buses via ports & I/O controllers PATA / SATA for secondary storage RS-232 serial (COM1,COM2) modems, UPSs, etc. parallel (LPT1) printers Ethernet data communications & networking USB (1.1, 2.0, 3.0) general hi-speed serial I/F IEEE1394 / ilink / Firewire for DVRs SCSI storage for high-performance servers CSC400 - Computer Hardware & Software 11 Device I/O Models I/O devices are categorized into 2 types: 1) block data transferred in "blocks" 512 Bytes, 1KB, 2KB ex: storage, LAN drivers 2) character "byte at a time" ex: keyboards, mice, serial ports CSC400 - Computer Hardware & Software 12 CSC400 - Operating Systems 6

7 Device I/O Methods programmed I/O (PIO) processor handles all data transfers between memory & I/O devices programmatically interrupt I/O I/O device signals CPU asynchronously that an I/O transfer is needed; CPU responds via ISR direct memory access (DMA) DMAC handles block I/O transfers & interrupts processor when complete processor free to execute other code CSC400 - Computer Hardware & Software 13 Hardware Support for Operating Systems CSC400 - Operating Systems 7

8 Protection Mechanisms 1 processor execution modes: user mode restricts applications from certain "privileged" instructions and processor facilities (a.k.a. protected mode) I/O, "STOP", state control, exception handling supervisor mode all operations permitted (a.k.a. kernel mode) used by processor & memory control, device drivers, interrupt/exception processing CSC400 - Computer Hardware & Software 15 Protection Mechanisms 2 memory protection prevents processes from "stepping out of bounds" implemented via special processor registers: base: defines starting physical address of process space range: defines length of process space violation results in "address exception" ex: pointer dereference problems in C CSC400 - Computer Hardware & Software 16 CSC400 - Operating Systems 8

9 OS Use of Protection robust OSs exploits CPU mode by running the OS kernel in supervisor (kernel) mode and all utility & user programs in protected mode ex: Unix was not ported to PCs until Intel added supervisor mode to the and memory protection to provide individual process an isolated, "virtual memory space" CSC400 - Computer Hardware & Software 17 Bootstrapping term used to describe the system initialization process of bringing an OS to a ready state starts from a small, non-volatile boot memory (ROM, i.e. BIOS) minimal system initialization to load boot code from secondary memory to main memory then transfers CPU control to boot code to load and startup OS proper CSC400 - Computer Hardware & Software 18 CSC400 - Operating Systems 9

10 Timers / Clocks used by OS for timing-related issues interval timer to support concurrency via process switching analogy: alarm clock TOD clock to track "wall clock time" typically battery backed-up CSC400 - Computer Hardware & Software 19 Computer Software CSC400 - Operating Systems 10

11 Language Hierarchy machine / assembly language of the processor, based on binary assembler: a machine language compiler interpreters perform high-level language translation "on the fly" compilers convert high-level to machine language CSC400 - Computer Hardware & Software 21 HLLs FORTRAN (1950s, IBM) scientific computing BASIC (1960s) simple, learning COBOL (1950s) business apps C (1970s) / C++ (1980s) systems programming Java (1990s, Sun) portable web apps. C# (2000, Microsoft) Windows/.NET Python (1991) GP HLL TIOBE index: CSC400 - Computer Hardware & Software 22 CSC400 - Operating Systems 11

12 Programming Paradigms imperative / procedural a modular, organized approach to s/w development based on processes/functions of the s/w ex: Pascal, ADA, FORTRAN object-oriented (OO) a data-centric development strategy based on s/w objects which have properties/attributes and behaviors/methods ex: C++, C#, Java, Python, Arduino CSC400 - Computer Hardware & Software 23 Software Development Steps editing for source code maintenance compilation translation from source code to object code linking integration of multiple s/w object modules into a single executable supports libraries of object code loading actual binding to memory locations prior to execution CSC400 - Computer Hardware & Software 24 CSC400 - Operating Systems 12

13 'X'-ware hardware the physical components of a computer software executable code loaded from secondary storage into main memory i.e. RAM (is volatile) firmware s/w that has been stored in nonvolatile primary memory i.e. ROM/Flash; ex: BIOS, embedded systems vaporware software delivered after its due date (or not at all) CSC400 - Computer Hardware & Software 25 CSC400 - Operating Systems 13