Unit 3: Hardware

Unit 2 Curriculum

Unit 3.pdf

Take aways:

CPU - Central Processing Unit
CPU does most of processing - (all if there is no GPU)
All systems have CPU's (smaller versions called microprocessors exist in domestic appliances and embedded systems)
data is processed using Fetch-Decode-Execute cycle method
von Neuman architecture refers to systems which us FDE cycle and consist of input device(s), prosessing device(s), storage device(s) and output device(s)
CPU consists of multiple components with specific tasks to facilitate the processing of data - fetching, decoding, executing
- - ALU - where all the calculations take place
  - CU - manages all processing
  - PC - stores address of next instruction set
  - MAR - stores addresses of instruction sets
  - MDR - stores instruction sets
  - ACC - temporary storage space as calculations and instructions are being performed/processed
  - Bus - wires which link components along which data travels
CPU's can have single, duel or multiple cores - each core is a processor
Cache is small capacity, high speed RAM located close to processor
Clockspeed refers to how fast instructions can be processed

Actuators are output devices
sensors are input devices

Primary storage is directly accessed by CPU eg RAM, ROM
Secondary storage is directly accessed by CPU but is non volatile eg HDD, SSD
External storage are removable storage devices eg flash derive/memory stick - NOT "USB"!, external HD, cloud etc
Solid state storage - no moving parts eg memory stick, SSD
Magnetic storage - uses electromagnets to encode binary information onto platters or tape
Optical storage - uses lasers to read and write data (or used to in the olden days)
Virtual memory is created by the computer when it runs out of available RAM
Cloud storage refers to the use of remote storage platforms provided by servers which could be anywhere in the world and belong to someone else
WIthout a NIC your device can not connect to a network
The NIC stores the MAC address for the device
MAC and IP addresses are written in hexadecimal
MAC is like a name, it never changes
IP is like an address or location - it can change
IPv4 ran out of IP addresses so was replaced by IPv6
IP and MAC addresses are needed to identify where to send data travelling across a network

The Central Processing Unit

Unit 3a.pptx

Unit 3c.pptx

FDE Cycle

Fetch

Decode

Execute

The Little Man Computer

The LMC was created to demonstrate how the CPU processes data and turns it into information.

It models von Neumann architecture

The LMC is a simulator that has many of the basic features of a modern computer that uses the Von Neumann architecture (a central processing unit consisting of an arithmetic logic unit and registers, a control unit containing an instruction register and program counter, input and output mechanisms, and RAM to store both data and instructions).

Using the LMC enables us to visually learn how the different components of the CPU work together to process data, we can observe the processes in real time - aka the speed of light, or we can slow the LMC down so that we can watch the complexity of processing step by step.

Unit 3b.pptx

LMC

Use this Link to LMC Simulator then tyoe the following code into the left hand Assembly Language area:

INP

STO 42

INP

ADD 42

OUT

HLT

Then click submit to load your program into translate your program into assembly language and load it into RAM - notice how the registers have been populated with numeric code.

Click the grey options button at the bottom of the simulator, and select 'Default Fast' from the drop down menu

Then run your code, you will see it asks you to enter 2 numbers and then it adds them together and outputs the result

Now click the grey Options button again and this time select default slow to watch what the CPU does at the speed of light ...

Factors which influence the performance of a CPU

A CPU contains an internal clock which controls the speed at which instructions are processed.

The speed is measured in hertz, the CPU with a speed of 1 hertz is able to processes one instruction per second

Most modern computers measure closckspeed in GHz (gigahertz), a CPU with a clockspeed of 2 GHz can process 2 billion instructions per second, if it has 2 cores it can process 2 x 2 billion instructions per second

Overclocking

Overclocking enables users to increase the clockspeed of a CPU, however this is against manufacturers recommendations and will invariable result in burning out your device.

Input and Output devices

In order for a processor to process data, it must first receive data and instructions, as users, er use input devices to do this.

by clicking or moving a mouse, by pressing a key on a screen or keyboard, by touching a trackpad, we can manually inpur data and information into a computer device.

By using sensors and scanners we can automate the input process

We need output devices to display the information that has been processed

Storage

We need to store data on computers constantly!
Sometimes it is temporarily as in the way all the programs that we are currently running are stored in RAM but they will all be wiped once the computer is powered off.

Sometimes we need to store data permanently like BIOS and POST which is stored in ROM chips or our OS and software which is stored on the hard drives or files stored externally - before being loaded into RAM for use.

Magnetic Storage

These are the oldest of the commonly used storage devices, but are still the most widely used.

Magnetic Hard Drives are used to store data and programs on desktops and laptops
Magnetic tape drives are usually used for large server / systems backups.

Advantages

Cheap Storage per MB (especially tape drives!)
Relatively quick read / write speeds.

Disadvantages

Easily broken if dropped
Slow read /write compared to new SSD drives.
High energy uses as it uses moving parts (lower battery life on laptops)

Magnetic storage media and devices store data in the form of tiny magnetised dots. These dots are created, read and erased using magnetic fields created by very tiny electromagnets.

In the case of magnetic tape the dots are arranged along the length of a long plastic strip which has been coated with a magnetisable layer (audio and video tapes use a similar technology).

In the case of magnetic discs (e.g. floppy disc or hard-drive), the dots are arranged in circles on the surface of a plastic, metal or glass disc that has a magnetisable coating.

Solid State Storage

Solid state drives are non-volatile storage devices capable of holding large amounts of data.

They use NAND flash memories, giving them the advantage of having no mechanical moving parts and therefore immediate access to the data.

Optical Storage

Optical storage is any storage type in which data is written and read with a laser. Typically, data is written to optical media such as compact discs (CDs) and digital versatile discs (DVDs).

Small capacity and vulnerable to damage.

Vertual Storage

Vertual storage is a technique employed by operating systems when they run out of space in RAM

Data is stored in any available space in secondary or conected external devices instead of RAM.

This means that data takes longer to be fetched to the CPU for processing and thus the system begins to lag, if the computer runs out os space the whole system will crash