complete CS (mocks + security)

what does CAD stand for

computer aided design

what is CAD

use of computer software to design new products in 3D, sent to CAM machines

what does CAM stand for

computer aided manufacture

what is CAM

using computers to control machines to produce goods

why is CAM better than human

fast, accurate and can continue working 24/7 (humans need rest)

but…

machines can go wrong, servicing of equipment, can break

CAM is also good (for sustainability reasons…)

can reduce waste of materials

what is additive manufacturing, example

building it one _____ at a time

creating an object by building it one layer at a time, 3D printingwhat

what is subtractive manufacturing, example

creating an object by cutting away at a solid block of metal

digital values are ____

discrete

binary:

1 represents a ___ ____

0 represent a ____ _____

1 - high voltage

0 - low voltage

how to convert binary to denary

• Starting from the rightmost digit (least significant bit), assign powers of 2.

  • The rightmost bit is 202^020, the next is 212^121, then 222^222, and so on.

• Multiply each binary digit (0 or 1) by its corresponding power of 2.

  • Add up all the results.
    
    
    

convert 10110110 into denary

how to convert denary to binary (small numbers) e.g. 15

1. write out powers of 2

2. write 1 under biggest power that can fit into denary number

3. same for remainder

how to convert denary to binary (larger numbers) e.g.185

1. by 2 and note the remainders:

2. Write the remainders from bottom to top

convert 228 into binary

write out conversion table for den/hex/bin

how to convert hex to denary (by positional value) e.g. 38B

how to convert hex to binary (by positional value) e.g. 38B

how to convert binary to hex (by nibbles) e.g. 011111010010

how to convert denary to hex e.g. 23

• Divide 23 by 16:

  • 23÷16=1 remainder 7.

  • (7÷ (16^0 so 1)) = 7

• Write the result:

  • Quotient = 1, Remainder = 7.

• Combine the digits: 17 (Hexadecimal).

how to convert denary to hex e.g. 458

1. write out powers of 16, as many digits as denary number

2. how many 16² fit into 458, 458÷256 = 1, remainder 202

3. how many 16¹ fit into 202, 202÷16 = 12, remainder 10

4. so you have 1, 12 (C in hex), and 10 (A in hex)

5. 1CA

binary addition rules (each combo for 1, 0)

• 0 + 0 = 0

• 1 + 0 = 1

• 1 + 1 = 10

• 1 + 1 + 1 = 11

carry over

4 reasons to use hex

• less display space, faster to enter data (16 bytes as just 4 hex digits)

• EASIER to identify values

• EASIER to spot errors

• (more human friendly)

• easier to convert back to binary if necessary

4 uses of hex

• colour coding e.g #FFFFF

• low level programming (e.g. assembly): quicker, easier, less error prone

• addresses: both IP and MAC (IPv6 uses hex)

• error messaging: in embedded systems e.g. lifts, bc hex takes up less screen space than long binary strings

what are the 4 logic gates

NOT
AND
OR
XOR

NOT gate symbol and truth table

AND gate symbol and truth table

OR gate symbol and truth table

at least one:

XOR gate symbol and truth table

Exclusive or (only 1)

define validation:

automatic checking of data to ensure only possible, sensible, reasonable data is accepted

describe: range

number must be in a specified range

length

length of inputted characters must match specified number of characters

type

data inputted must be of correct data type

look-up

a specific character must be included

format

data must be incorrect format e.g. 2 characters then 6 integers, etc.

presence

ensures some data has been entered

uniqueness

to check data entered is unique within a system

generic steps for systems approach (3 words)

input → process → output

what is an input device

input device takes a real world signal (e.g. light, temperature), turns it into an electronic signal (e.g. current, voltage)

what is an output device

output devices turn an electronic signal into a real world signal (e.g. light, sound, movement)

example of input vs output devices:

input: LDR, thermistor, switches

output: LEDs, sound devices

define driver

to what exactly does it tell

a small program which tells an operating system how to respond to a particular hardware that is attached to the sustem

when is a driver needed + how does it help

when a process device can’t provide a high enough signal for the output device to work correctly

drivers us transistors to amplify current or to control the direction of the movement of the motor

explain how a closed loop feedback system works, and example

the output signal of a central heating system has a direct effect on the input

e.g. central heating system:

output signal (temperature) is fed back into input, so that the system knows when to turn the heater off

what is a transducer

any device that converts between an electrical quantity and a real-world quantity.

what does a sensor do

known as what kind of transducer

input device which detects real-world quantities, then converted into an electrical signal

real world quantity, e.g. sound, light

input transducer

what does an actuator do

takes an electrical signal and converts it into a physical form

e.g. motor, speaker

output transducer

analogue signals cover all the ____ number of different voltage values

infinite

any digital systems needs signals from sensors to be translated to ____ signals before they can be processed

what does this

digital signals

ADCs

what does ADC stand for

analogue to digital converters

what do ADCs do/how does it work

devices which take samples of continuous analogue signals and encode the samples into discrete binary code

diagram, unofficial

if the ADC is located outside the sensor, the sensor is _____

analogue

if the sensor has the ADC built into it, it is a ______ sensor

digital

alternate definition for actuator (movement)

mechanical output devices that produce movement

directions of data transmission (3)

simplex: one direction. sending or receiving data from a device

DATA ONLY GOES ONE WAY

duplex: sending data to and from devices

(BOTH DIRECTIONS, BUT ONLY ONE AT A TIME)

full duplex: BOTH DIRECTIONS AT THE SAME TIME

define interface

a point at which two computer systems communicate

what is a serial interface

allows serial communication between a microcontroller to a microcontroller/processor using a SERIAL cable

(one wire to transmit, one to receive)

define serial communcation

the process of sending data one bit at a time, sequentially, over a single communication channel

what is SYNCHRONISED communication

each bit is synchronised to the oscillations of an on board clock

(continuous stream of data)

steps for synchronised serial communication:

1. bits into bytes

2. when are timing signals sent/with what

3. speed? and so example of when used

1. receiver counts how many bits were sent and reassembles the bits into bytes

2. timing signals are sent WITH the data

3. FAST as only data bits are sent (so used when speed is important e.g. network connections)

asynchronous serial communication: how is data packaged

how are they sent across

sent as a packet

files are broken up into many packets and reassembled at the receiving endd

what is the format of a packet

a frame:

contains all info required to interpret data at the receiving end

what do communicating devices agree on their protocol before transmission:

bit pattern and bit rate (bit’s per second)

what does this mean for speed

slightly slower than synchronous

what does usb stand for

universal serial bus

advantages of USB and USB-C (3, 3)

disadvantages (2)

• fits/works both ways

• can run basically any modern protocol

• more power than older USB

• lots of compatibility

• very fast data transmission

• automatically detects if the correct driver is installed

• max cable length only 5 metres

• older standard becoming obsolete

why is serial transmission reliable

• bits stay in the correct order, less skewed/unsynchronised data as only 1 wire is used

define parallel communication

several bits are sent at the same time, on a link with several channels in parallel with each other

serial vs parallel (2)

• parallel faster than serial

• but parallel is not reliable over long distances, so mainly found on very short communication channels of printed circuit boards (where channels are fixed in positions and synchronisation is likely to be undisturbed)

  • there may be signal degradation, timing issues so data is wrongly aligned, etc.

what provides the timing for parallel

• oscillations of the system clock

define port, hardware, software

hardware: connection point/interface between a computer and an external or internal hardware device

software: a virtual point where network connections start and end

define protocols

set of rules for communication between devices

what is the baud rate

how fast data is sent over a serial line

(if it goes too high you might get errors)

what is parity checking

basic principle: something to do with the bits being total even or odd idk

used in data transmission to check for errors: if parity is incorrect, an error is detected

what is the time to live variable/what does it do?

• limits ____

• prevents ____ from circulating _______ly

• determines when data should _____

TTL (Time To Live) is a value that limits how long a piece of data should exist or be considered valid. It's commonly used in networking to prevent packets from circulating indefinitely and in caching to determine when data should expire.

a microcontroller is a ____, ____ purpose computer. they can do how many things?

a microcontroller is a TINY, SINGLE PURPOSE

they can do ONE thing well

microcontrollers are ______ in some other device. so a microcontroller can be called an _____ ______

EMBEDDED in another device

EMBEDDED CONTROLLER

microcontrollers are ____ to one task and run one specific program.

where is this program stored, does it change?

dedicated to ONE TASK/PROGRAM

stored in ROM

does not change

microcontrollers are often ___-power devices

LOW POWER

a microcontroller often has what two dedicated devices:

input device and output device

microcontroller size and cost?

small and low cost

microcontroller features (6)

• small

• low cost

• low power

• often has dedicated input/output device

• dedicated to one task, run one specific program stored in ROM (doesn’t change)

• often embedded inside another device (e.g. washing machine)

what does the CPU of a microcontroller have in it

everything:

• EEPROM, timer, CPU, RAM, ROM, input/output

analogue vs digital

analogue: continuous signals

digital: discrete signals

hard disk storage stores data/instructions in the ___ term

LONG TERM

a microprocess is used in a ____ purpose computer, how many programs can it run

general purpose computer, can run thousands of programs

the central chip of a microprocessor has how many peripheral chips

several

what do microprocessors use to control/manage multiple processes at the same time. e.g. on computers

operating system

microcontroller vs microprocessor - 2

microprocessor can run thousands of programs, microcontroller just one

microprocessor has several peripheral chips, microcontroller has everything embedded in the CPU

microcontroller

The Data Science Cycle

Steps in order:

1. Problem Formulation

2. Getting Data

3. Exploring Data

4. Analysing Data

5. Communicating Results

Problem Formulation

Start with questions or explore data to find patterns

Getting Data

Import CSV (Comma-Separated Values) files and clean up messy/missing data

Exploring Data

Look for patterns and create basic plots to understand your data

Analyzing Data

Find connections between variables and test your questions

Communicating Results

Create clear visuals and explain findings for your audience

.read_csv()

Import CSV files into Python

.describe()

Get quick statistics about your data

.groupby()

Organize data by categories for comparison