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hardwareand

operating systemsbasics

BY

SA

• client/workstation (PC)• server (responds to requests from network)• hand-held (phone, audio player)• embedded system (toaster, car)• mainframe (a big server)• supercomputer (a many-processor system)

RAM (Random Access Memory)

• addressable by the CPU• volatile• faster than storage• code and data of running programs

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programming model(simplified conception of a processor

for sake of programmers)

instruction(a sequence of bits understood by the

processor to signal a certain action)

• copy bytes• arithmetic• bit logic• jumps

register(a small memory area in a processor)

• status• general purpose

ISA (Instruction Set Architecture)

x86 (IA-32, x86-64)ARMMIPSMotorola 68k

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call stack(local variables)program memory

heap(everything else)

code

frame of main

frame of cat

frame of dog

frame of fish

frame of bird

frame of lama

stack space

• local variables• argument values

top of stack

top of stack

top of stack

top of stack

top of stack

top of stack

frame of moose

stack space

frame of main

frame of cat

frame of dog

frame of fish

frame of bird• local variables• argument values• return address

top of stack

top of stack

big-endian vs. little-endian(the order in which the bytes of a register are copied

from registers to memory and vice versa)

big-endian vs. little-endian(the order in which the bytes of a register are copied

from registers to memory and vice versa)

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processor registersprocessor cache

random access memoryhard drives

speed, cost

capacity

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CPU

registers

device

read/write

port-mapped I/O vs. memory-mapped I/O

output register 2 to port 0x44 98

copy register 5 to address 0x66 2C 1A 32

ports

memory addresses

RAM

0x00 00 00 00

0xFF FF FF FF

byte 0

byte n

port 0

port n

devices

memory addresses

RAM

0x00 00 00 00

0x00 01 00 00

0xFF FF FF FF

0x00 00 FF FF

byte 0

byte n

devices

(code periodically checks device registers to see if the device needs the CPU to do something)

polling

CPU

registers

deviceinterrupt line

(code periodically checks device registers to see if they need the CPU to do something)

polling

1. device sends interrupt signal to CPU2. CPU saves state of whatever it was currently doing3. CPU jumps to address corresponding to interrupt

number in the interrupt table

interrupt

0x76 00 00 00interrupt 0

0x20 15 10 00interrupt 1

0x82 87 95 94interrupt 2

0xA2 22 00 10interrupt 3

0xFF 31 21 14interrupt 4

0xFF 31 01 11interrupt 5

0xFF 90 44 44interrupt 6

0xFF 31 01 11interrupt 7

… …

(code periodically checks device registers to see if they need the CPU to do something)

polling

1. device sends interrupt signal to CPU2. CPU saves state of whatever it was currently doing3. CPU jumps to address corresponding to interrupt number

in the interrupt table4. CPU returns to whatever it was doing before the interrupt

interrupt

hardware exception (a condition which causes the CPU to jump to a pre-determined address)

0x76 00 00 00exception 0

0x20 15 10 00exception 1

0x82 87 95 94exception 2

0xA2 22 00 10exception 3

0xFF 31 21 14exception 4

… …

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• Instruction Set Architecture• byte size• word size• address size• cache speeds and sizes• big-endian vs. little-endian• ports vs. memory-mapped i/o• number of processors/cores

boot firmware

CPU

registers

BIOS

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boot firmware

CPU

registers

BIOS

operating system(manages the hardware and running programs)

• load and manage processes• provide “interfaces” to hardware via system calls• provide a filesystem• provide a basic user interface

Windows(series of OS’s from Microsoft)

• Windows 7• Windows Server 2008• Windows CE

Unix(a family of OS’s)

• Linux• BSD• OS X

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OS

device driver(plug-in to the OS to control a particular device)

device device device

driverdriverdriversoftware

hardware

B A B C CB AB A

time

A BC BCA C C

CPU

CPU 2

processOS

1. CPU receives interrupt2. interrupt stores state of currently running code3. interrupt invokes handler4. interrupt handler invokes the scheduler5. scheduler selects a process6. scheduler “configures” CPU for that process7. scheduler jumps execution to that process

pre-emptive multitasking

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Process C

Process B

OS

Process A

0x00 00 00 00

0xFF FF FF FF

stack

heap

code0x 00 00 00 00

0x FF FF FF FF

heap

heap

RAM

byte 0

byte n

stack

heap

code0x 00 00 00 00

0x FF FF FF FF

heap

heap

RAM

byte 0

byte n

HD

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Process C

Process B

OS

Process A

jump to system call code via special instruction

RAM

0x76 00 00 00system call 0

0x20 15 10 00system call 1

0x82 87 95 94system call 2

0xA2 22 00 10system call 3

0xFF 31 21 14system call 4

0xFF 31 01 11system call 5

0xFF 90 44 44system call 6

0xFF 31 01 11system call 7

… …

stack

code0x 00 00 00 00

0x FF FF FF FF

heap

heap

allocated with system call

heap

heap

allocated with system callallocated with system call

allocated with system call

stack

code0x 00 00 00 00

0x FF FF FF FF

heap

heap

heap

deallocated with system call

stack

code0x 00 00 00 00

0x FF FF FF FF top of stack

stack boundary

heap

heap

heap

stack

code0x 00 00 00 00

0x FF FF FF FF

top of stackstack boundary

heap

heap

heap

created

waiting running

blocked

terminated

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HD

partition 1

partition 2

partition 3

HD

partition 4

flash drive

partition 5

CD-ROM

partition 6

partition 7

file 35

file 7

file 61

file 3

directory 21

directory 86

root directory

partition 1

C: H: D:

C:/H:/D:/

partition 2 partition 3

partition 1

C: H: D:

C:/adams/nixonH:/taylor/polk/hayesD:/garfield

partition 2 partition 3

partition 1

/banana / /lemon/apple

partition 2 partition 3

partition 1

/banana / /lemon/apple

/banana/adams/nixon/taylor/polk/hayes/lemon/apple/garfield

partition 2 partition 3

IPC (Interprocess Communication)

filespipes

socketssignals

shared memory

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