Hardware Flashcards
Hardware
-physical components and the way they are connected
Software
-programs or lists of instructions to control the hardware to work properly
Peripherals
-the additional components
CPU
- Central processing unit
- is responsible for controlling most aspects of the computer system
- functionality of every computer system is centred on a processor
- function is to ~ process data, perform arithmetic and logical operations, store and retrieve information, communicate with peripheral devices
- every processor had its own language called machine language
- is the brain of the computer
CPU inside parts
CPU consists of three main parts
- control unit
- arithmetic/logic unit
- registers
Computer hardware
- CPU: central processing unit
- Memory: Dynamic RAM, static RAM
- Storage devices: hard drive
- Input devices: keyboard, mouse
- Output devices: screen, printer, network
- Communication devices: network, infrared, Bluetooth
Graphics board
- not all computer have them, sometimes the graphics capability built into motherboard
- can include its own processor and RAM
Computer Architectures
-von Neumaann (Princeton) Architecture (used in most computers)
Single memory source, requests instructions and data from a single location
-Harvard Architecture
Processor communicates two ways with an instruction memory source and a data source
-days and instructions kept desperate
Fetch - decode - execute
- Every general processor operates on the principle of fetch-decode-execute cycle
- A machine instruction is
- fetched from a program memory
- decoded and
- executed - The cycle is driven but a series of clock pulses
Timing (clock)
- All computers work on some sort of timing signal that is known as clock
- Clock is a periodic timing signal whose period is called a cycle
- The number cycles/second is called frequency whose units are Hertz
- Each processor operates at a certain frequency: the processor speed
Control unit
-Decides what to do next
-CU is responsible for fetching, decoding and executing instructions
-The CU issues logic signals that enables registers to output to, or receive info from, using an internal data pathway
Example
-memory operations
-arithmetic/ logical operations
-branch: choosing possible courses of action
Arithmetic/Logic Unit
- performs arithmetic and logical operations
- the CU fetches the appropriate data and issue a signals to the ALU to perform certain operation
- Arithmetic operations: add/Sub/Mult
- Logical operations: compare numbers to see which greater, check if Boolean is true
Registers
- are memory/like locations inside CPU
- for data and instructions being used right now
- hold operates being used in current arithmetic or logical operation or the result
- A typical CPU has only a few hundred to a a few thousand bytes of registers
System Bus Model
-communication between CPU, memory, and an input/output unit is handled by a shared pathway called the system bus
Storage
Two major categories of storage
- Primary (fast memories, small size)
- cache
- Main memory (RAM) - Secondary (slow memories, large size)
- hard disk
- removable
Memory heirarchy
From smallest to biggest and fastest to smallest
- registers
- on-chip cache
- secondary level cache (SRAM)
- main memory (DRAM)
- secondary memory (DISK)
- external memory
Primary storage
- Where days and instructions reside when they’re being used by a program that is currently running
- volatile: disappear when the power turned off
- main memory and cache
Cache
Cache memory is where data and instructions reside when they are going to be used very soon or have been just used
-is nearly the same speed as the CPU so the CPU doesn’t have to wait nearly as long for stuff in cache
Main memory (RAM)
Is here data and instructions reside when a program that is currently running is going to use them at some point during the run
- is made up of locations or cells
- each location has an address, and a value that can be looked at or changed
RAM: Random Access Memory
- memory that the CPU can look at and change arbitrarily( can load form or store into any location at any time)
- often use Main Memory, Memory, and RAM interchangeably
ROM: Read Only Memory
Memory that the CPU can look at arbitrarily, but cannot change
Secondary Storage
- where data and instructions reside that are going to be used in the future
- non-volatile: data doesn’t disappear when power is turned off
- must slower then RAM so cheaper and larger
Bits
- binary digit
- tiniest possible piece of memory
- made of tiny transistors wired together
- 0 or 1
Byte
-sequence of 8 contiguous bits
- on most platforms is the smallest addressable piece of memory
0~255 or -128 - 127
KB, MB, GB, TB, PB
Kilobyte: 2^10 thousand bytes Megabyte: 2^20 million bytes Gigabyte: 2^30 billion bytes Terabyte: 2^40 trillion bytes Petabyte: 2^50 quadrillion bytes Exabyte: 2^60 quintillion bytes
Nibble
4 bits
Word
Sequence of 4 or 8 bytes
