prepare for interview Flashcards
Hard Disk
Non-volatile data-storage device. rotating magnetic disk.
Uses magnetic storage to store and retrieve digital information. composed of one or more rapidly rotating platters coated in thin magnetic material. Data accessed in random-access manner (can be stored and retrieved in any order).
Non-volatile: retain stored data when powered off.
Computing Machine
Machine that does something based on input, and produces output
Turing Machine
‘the blueprint of modern computing’. ‘Machine’ that recieves a tape of 1’s and 0’s, reads it, changes 1’s to 0’s and 0’s to 1’s according to instructions. the tape that used to be a question becomes an answer to the question.
Initially just a theoretical idea of a device that, when given a tape of whatever needed length of 1s and 0s, reads the tape and changes the 1s and 0s in accordance with its instructions. the tape of 1s and 0s starts as a question, and when the turing machine is finished with it, becomes the answer.
Von-Neumann Architechture
computer model designed by John Von-Neumann in 1945.
Input -> Memory -> Output
V> Processor (Control Unit <->Arithmetic Logic Unit)
+ Input stored as command in Memory,
+ Processor fetches command from Memory,
+ CU manages commands and input/output,
+ ALU handles calculations,
+ CU stores complete commands in memory,
+ Output is displayed.
Operating System
Program that allows a user to interact with the computer.
History of Linux
developed by Linus Torvalds.
started in 1991 as a pet project,
became community open source project
Linux 1.0.0 launched in 1994
What is Linux?
Open source Operating System. Android is based in Linux.
CPU
Central Processing Unit. interprets and executes all instructions. consists of single microprocessor, but stronger mainframes use one or more. contains CU and ALU (Command Unit, Arithmetic Logic Unit)
- CPU cache
Stores temporary files.
Small chunk of memory on the computer’s processor that stores basic computer instructions that were recently or are frequently used.
Makes processing go faster because frequent data close to CPU
RAM
Computer memory that can be read and changed in any order.
Typically used to store working data and machine code.
ROM?
EPROM?
Read-Only Memory. Non-volatile memory, cannot be electronically modified after manufactury.
Erasable Programmable, read only memory. can be erased if exposed to certain ultraviolets.
BIOS
Basic Input Output System
Boot Loader
Computer instructions in ROM in motherboard chip.
Controls input and output operations.
Loaded into memory on startup, performs POST (power on self test), then loads OS from hard drive into memory.
BUS (Address, Data, Control)
Set of wires carrying signals between devices. connect CPU, memory and I/O devices.
Address bus: carries the address of memory location/ IO device CPU is communicating with
Data bus: carries data between CPU and memory / IO device
Control Bus: carries control signals, telling IO devices what to do
I/O device
Any external device that could send input or receive output.
(secondary storage, keyboard, mouse, monitors, printers)
File system
The way in which files are named and placed logically for storage and retrieval.
NTFS, NFS and ext4 are file systems.
Program
Set of code and instructions meant to complete a task.
Process
Running instance of a program
USB
Universal Serial Bus
Technology that connects computers with external devices
Serial Port
Connector that sends data one bit at a time.
May be connected to a computer.
Parallel port
Device Connector,
sends/receives several bits of data simultaneously using more than one wire.
RS-232
slow but reliable standard transferring data as voltage signal. relatively slow, used still for modems, printers, and other peripherals.
(U)EFI
Unified Extensible Firmware Interface.
Boot Loader, Replacement for BIOS, controls startup process. supports larger hard drives, faster boot times, improved security, adds GUI to configure UEFI settings.
Boot Loader
Loads an operating system when a computer is turned on. Stored in non-volatile memory (ROM)
GRUB/LILO
GRUB: new boot loader with multi-OS device management. Supports Windows, Linux, UNIX, macOS, BSD, and Solaris.
LILO: older boot loader with single OS device management. Only supports Linux.