Computer Hardware Flashcards
CPU (Central Processing Unit)
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)
GPU (General Processing Unit)
provides the operating system desktop
Memory
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.
Timers
Allow softwares to be time dependent for synchronizing and so on
Interrupt controller
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
general purpose input output (GPIO)
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.
USB
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.
PCM/I 2 S
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).
Direct memory access (DMA) controller
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.
I 2 C master
Inter-integrated circuit often employed for connecting lower-speed peripheral chips to control processors and microcontrollers.
I 2 C/SPI (Serial Peripheral Interface) slave
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.
SPI Interface
Serial interfaces, accessed via the GPIO pins and allowing the daisy chaining of several compatible devices by the use of different chip-select pins.
Pulse width modulation (PWM)
A method of generating an analogue waveform from a digital signal
Universal asynchronous receiver/transmitter (UART0, UART1)
Used for serial communication between different devices.
Benefits of Raspberry pi
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.
Status LEDs
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)
Central Processing Unit
What the computer does - The programs (Made out of a large number of transistors)
Memory
What the computer knows - The data (Made out of a large number of transistors)
Registers
Certain limited number of storage locations
Specific purpose registers
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.
Chapter 2
Chapter 2
Process management:
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.)
File Management
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.
Peripheral management
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.
Network management
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.
User account management
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.
Security
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.
User Interface management
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.
RAM (Random Access Memory)
short term memory where data is stored as the processor needs it.
