Computer Hardware

Question 1

CPU (Central Processing Unit)

Answer 1

Performs data processing under control of the operating system (a CPU with a core on most raspberry pi models and a CPU with four cores on the raspberry pi 2 and raspberry pi 3)

Question 2

GPU (General Processing Unit)

Answer 2

provides the operating system desktop

Question 3

Memory

Answer 3

Permanent memory used as registers for CPU and GPU operation, storage for bootstrap software, the small program which starts the process of loading the operating system and activating it.

Question 4

Timers

Answer 4

Allow softwares to be time dependent for synchronizing and so on

Question 5

Interrupt controller

Answer 5

Interrupts allow the operating system to control all of the computer resources, know when the CPU is ready for new instructions and and much more

Question 6

general purpose input output (GPIO)

Answer 6

provides layout and enables control of connections, inputs, outputs and alternative modes for the GPIO pins that enables the Raspberry pi to manage circuits, devices, machines and so on. Turns Raspberry pi into an emmedable control system.

Question 7

USB

Answer 7

Controls the USB services and provides the Universal Serial Bus protocols for input and output, thus allowing peripherals of all types to connect to the Raspberry Pi’s USB receptacles.

Question 8

PCM/I 2 S

Answer 8

Provides pulse code modulation (PCM, which converts digital sound to analogue sound such as speakers and headphones require) and known as Inter-IC Sound, Integrated Interchip Sound, or IIS, a high-level standard for connecting audio devices).

Question 9

Direct memory access (DMA) controller

Answer 9

Direct memory access control that allows an input/output device to bypass the CPU and send or receive data directory to the main memory for purposes of speed and efficiency.

Question 10

I 2 C master

Answer 10

Inter-integrated circuit often employed for connecting lower-speed peripheral chips to control processors and microcontrollers.

Question 11

I 2 C/SPI (Serial Peripheral Interface) slave

Answer 11

The reverse of the preceding bullet point. Allows outside chips and sensors to control or cause the Raspberry Pi to respond in certain ways; for example, a sensor in a motor detects it’s running hot and the controller chip causes the Raspberry Pi to make a decision on whether to reduce the motors speed or stop it.

Question 12

SPI Interface

Answer 12

Serial interfaces, accessed via the GPIO pins and allowing the daisy chaining of several compatible devices by the use of different chip-select pins.

Question 13

Pulse width modulation (PWM)

Answer 13

A method of generating an analogue waveform from a digital signal

Question 14

Universal asynchronous receiver/transmitter (UART0, UART1)

Answer 14

Used for serial communication between different devices.

Question 15

Benefits of Raspberry pi

Answer 15

It’s really small— all models are credit-card sized or smaller.
You can replace the operating system in seconds simply by inserting a new SD or microSD card for almost instant reconfiguration.
The Broadcom SoC gives the Raspberry Pi more interfaces, communications protocols and other features out of the box than conventional computers that sell for many times the price.
The GPIO pins (see Figure 1-4) allow the Raspberry Pi to control real-world devices that have no other method of computer input/output.

Question 16

Status LEDs

Answer 16

ACT (activity, green): Indicates an SD card is plugged in and accessible

PWR (power, red): Indicates power is present

FDX (full duplex, green): Indicates a full duplex local area network (LAN) is connected

LNK (link, flashing green): Indicates activity is happening on the

LAN 100 (yellow): Indicates a 100-Mbit/s LAN is connected (as opposed to a 10-Mbit ­network)

Question 17

Central Processing Unit

Answer 17

What the computer does - The programs (Made out of a large number of transistors)

Question 18

Memory

Answer 18

What the computer knows - The data (Made out of a large number of transistors)

Question 19

Registers

Answer 19

Certain limited number of storage locations

Question 20

Specific purpose registers

Answer 20

Program counter: A program counter register holds the address of the next machine instruction to be brought in from memory for execution. It “keeps the place” in a computer program.

Status: A status register (sometimes called a flags register) holds a value divided into single bits or groups of bits. Each bit or group is updated with the status of something the CPU has just done. When the CPU compares the values in two registers, a singlebit “equal” flag will be set to either 1 (if the values were equal) or 0 (if the values were not equal). This allows an instruction that follows the comparison to know which way the comparison went.

Stack pointer: A stack pointer holds an address in memory where a data structure called a last-in-first-out stack is stored. Stacks are fundamental to CPU operation; we describe them in more detail in Chapter 4 in the section “Inside the CPU”.

Accumulator: The accumulator is a register that holds the result of arithmetic and logical operations. (It is so named because it was used to accumulate intermediate values during calculations in very early computers.) In modern computers, no single register is the sole location for arithmetic results, and the accumulator’s job has been redistributed to some or all of the general-purpose registers. However, some older machine instructions assume that a single register will hold the results of their operations, which is why the term has survived.

Question 21

Chapter 2

Answer 21

Chapter 2

Question 22

Process management:

Answer 22

The OS launches individual threads of execution for its own needs and the needs of users. It allocates execution time on the CPU among executing threads. If the CPU has multiple cores, it distributes processes among the cores. (More on this later.)

Question 23

File Management

Answer 23

The OS maintains one or more file systems, which allocate file storage space on disks and other mass-storage devices and manage the reading of data from files and the writing to and deletion of files.

Question 24

Peripheral management

Answer 24

The OS manages access to system peripherals like keyboards, mice, printers, scanners, graphics coprocessors and (in cooperation with file systems) mass storage devices. This is generally done through specialised software interfaces called device drivers, which are written for specific peripherals and may be installed separately, much like user applications.

Question 25

Network management

Answer 25

The OS manages the computer’s access to external networks (like local area networks and the Internet) through a collection of standard methods called networking protocols. The protocols are implemented in one or more pieces of software that, taken together, are called the network stack.

Question 26

User account management

Answer 26

management: All modern operating systems allow different users to have their own accounts on the computer. An account includes a unique login, a set of security rules called privileges and a private file space protected from manipulation by other users.

Question 27

Security

Answer 27

Scattered throughout an OS are mechanisms to keep running processes from interfering with one another and with the OS itself. Much of OS security is done by defining rules that specify what processes and users can and cannot do. Certain users called administrators or super users have powers that ordinary users do not have, in order to control the way the OS does its work.

Question 28

User Interface management

Answer 28

The OS manages user interaction with the computer through software mechanisms called shells. A shell may be as simple as a text command line in a terminal window, or it can be a full-blown windowed graphical environment like those used in Windows, Mac OS X and desktop implementations of Linux, including Raspbian on the Raspberry Pi.

Question 29

RAM (Random Access Memory)

Answer 29

short term memory where data is stored as the processor needs it.