1.3.6 Operating systems

DESCRIBE THE PURPOSE OF AN OPERATING SYSTEM
AN OPERATING SYSTEM HAVE A HUGE NUMBER OF DIFFERENT PURPOSES: - PROVIDES A USER INTERFACE
- ALLOWS MULTI-TASKING
- IT IS PROGRAMMABLE TO DO DIFFERENT THINGS
- ALLOWS BATCH PROCESSING OF DATA
- LOADING AND RUNNING OF SOFTWARE AND APPLICATIONS - USER ACCOUNT MANAGEMENT
- FILE MANAGEMENT
- PROCESSOR/MEMORY MANAGEMENT
- HAS SECURITY FEATURES
- MANAGES PERIPHERALS
 
SHOW UNDERSTANDING OF THE NEED FOR INTERRUPTS
INTERRUPTS ARE USED BECAUSE THERE ARE DIFFERENT PRIORITIES A COMPUTER WILL HAVE, AND THE COMPUTER NEEDS TO DEAL WITH THEM FIRST. FOR EXAMPLE, IF THE COMPUTER IS RUNNING LOW ON BATTERY, IT HAS TO TELL THE USER AND THEREFORE HAS TO INTERRUPT THE CURRENT PROCESS, AS IF IT WAITS UNTIL THE CURRENT PROCESS IS FINISHED, THE COMPUTER MIGHT HAVE RUN OUT OF BATTERY AND SHUT DOWN WHICH MAY CAUSE LOSS OF DATA.

1.3.5 Memory, storage devices and media

SHOW UNDERSTANDING OF THE DIFFERENCE BETWEEN: PRIMARY, SECONDARY AND OFF-LINE STORAGE AND PROVIDE EXAMPLES OF EACH, SUCH AS:
PRIMARY: READ ONLY MEMORY (ROM), AND RANDOM ACCESS MEMORY (RAM)
SECONDARY: HARD DISK DRIVE (HDD) AND SOLID STATE DRIVE (SSD); OFF-LINE: DIGITAL VERSATILE DISC (DVD), COMPACT DISC (CD), BLU-RAY DISC, USB FLASH MEMORY AND REMOVABLE HDD 
 
DESCRIBE THE PRINCIPLES OF OPERATION OF A RANGE OF TYPES OF STORAGE DEVICE AND MEDIA INCLUDING MAGNETIC, OPTICAL AND SOLID STATE
MAGNETIC WORKS IN SUCH A WAY THAT THE DATA IS ENCODED BY POSITIVE AND NEGATIVE CHARGES, WHICH REPRESENT THE 1’S AND 0’S.

OPTICAL WORKS IN A WAY CD’S DO, EITHER RED OR BLUE LASER IS SHONE, AND IN THE CD, THERE ARE PITS AND GROOVES, WHICH REPRESENT THE 1’S AND 0’S. SOLID STATE IS A BUNCH OF NAND GATES CONNECTED, AND THEY ARE CREATED IN A SUCH A WAY THAT THEY CAN STORE THE 1’S AND 0’S.
 
DESCRIBE HOW THESE PRINCIPLES ARE APPLIED TO CURRENTLY AVAILABLE STORAGE SOLUTIONS, SUCH AS SSDS, HDDS, USB FLASH MEMORY, DVDS, CDS AND BLU-RAY DISCS
SSDS ARE SOLID STATE, THEY ARE MADE FROM NAND GATES. HDDS ARE MAGNETIC STORAGE, AND THE DATA IS READ BY THE READ-WRITE HEAD WHILE THE DISK IS SPINNING. USBS USE FLASH MEMORY. DVDS, CDS AND BLU-RAY ARE OPTICAL STORAGE DEVICES, THEY USE A LASER TO READ INFORMATION (THE 1’S AND 0’S).
 
CALCULATE THE STORAGE REQUIREMENT OF A FILE
ONE CHARACTER IS A BYTE, IMAGES ARE RESOLUTION (HEIGHT X WIDTH) X BIT DEPTH. AUDIO IS CALCULATED BY BIT RATE.

1.3.4 Output devices

DESCRIBE THE PRINCIPLES OF OPERATION OF THE FOLLOWING OUTPUT DEVICES: INKJET, LASER AND 3D PRINTERS; 2D AND 3D CUTTERS; SPEAKERS AND HEADPHONES; ACTUATORS; FLAT-PANEL DISPLAY SCREENS, INCLUDING LIQUID CRYSTAL DISPLAY (LCD) AND LIGHT-EMITTING DIODES (LED) DISPLAY; LCD PROJECTORS AND DIGITAL LIGHT PROJECTORS (DLP)
INKJET PRINTERS - THESE ARE DEVICES THAT PRINT SOFT-COPY ITEMS INTO HARD-COPY ONES. IT USES INK AND SPRAYS DROPLETS OF INK TO CREATE AN IMAGE/DOCUMENT.
LASER PRINTERS - THESE ARE DEVICES WHICH USE DRY-INK INSTEAD OF WET INK LIKE THE INKJET PRINTER. IT USES STATIC ELECTRICITY (POSITIVE/NEGATIVE CHARGE) TO PRINT, AND THEN THE INK AND PAPERS IS HEATED TO BE FUSED.
3D PRINTERS - THESE DEVICES ARE USED IN CAD, WHERE IT PRINTS 3D OBJECTS USING DIFFERENT MATERIAL.
2D/3D CUTTERS - THESE CUT OBJECTS. THE DIFFERENCE BETWEEN 2D AND 3D IS THAT THEY 3D CAN RECOGNIZE X-Y-Z CO- ORDINATES. 3D CUTTERS CAN CUT: GLASS, CRYSTAL, POLYMER ETC.
SPEAKERS/HEADPHONES - DIGITAL DATA IS CONVERTED TO ANALOGUE DATA USING A DAC, THROUGH AN AMPLIFIER, THE DEVICE THEN PLAYS IT OUT LOUD.
LCD/LED DISPLAYS - LIQUID CRYSTAL DIODE/DISPLAY (LCD) & LIGHT EMITTING DIODE (LED) ARE DEVICES WHICH EMIT LIGHT, THESE ARE TINY AND MAKE UP COMPUTER SCREENS AND SUCH.
LCD/DLP PROJECTORS - THESE DEVICES (DIGITAL LIGHT PROJECTORS (DLP) GIVE OUT BEAMS OF LIGHT AND CAN BE SHOWN ONTO A LARGER SCREEN OR ONTO INTERACTIVE WHITEBOARDS 

DESCRIBE HOW THESE PRINCIPLES ARE APPLIED TO REAL-LIFE SCENARIOS, FOR EXAMPLE: PRINTING SINGLE ITEMS ON DEMAND OR IN LARGE VOLUMES; USE OF SMALL SCREENS ON MOBILE DEVICES INKJET PRINTERS - EVERYDAY-USE, PRINTING DOCUMENTS, PRINTING IMAGES.
LASER PRINTERS - EVERYDAY-USE, PRINTING DOCUMENTS, PRINTING IMAGES. BUT MUCH FASTER ALTHOUGH LOWER QUALITY.
3D PRINTERS - MODELLING, ART, VISUAL REPRESENTATION OF OBJECTS. 2D/3D CUTTERS - INDUSTRIAL USE, DESIGNING SPEAKERS/HEADPHONES - EVERYDAY-USE, CONCERTS ETC.
LCD/LED DISPLAYS - COMPUTERS, TV’S, NORMAL LIGHTING
LCD/DLP PROJECTORS - EVERYDAY-USE, MEETINGS, FOR INTERACTIVE WHITEBOARDS

 

1.3.3 Input devices

DESCRIBE THE PRINCIPLES OF OPERATION (HOW EACH DEVICE WORKS) OF THESE INPUT DEVICES: 2D AND 3D SCANNERS, BARCODE READERS, QUICK RESPONSE (QR) CODE READERS, DIGITAL CAMERAS, KEYBOARDS, MICE, TOUCH SCREENS, INTERACTIVE WHITEBOARD, MICROPHONES
2D SCANNERS - THEY REFLECT LIGHT ONTO A PAGE, AND THEY GET THE COLOUR OF THE PAGES BASED ON THE REFLECTION.
3D SCANNERS - THEY SEND RADIATION ALL AROUND THE OBJECT, AND THEY CALCULATE THE TIME AND ENERGY LOST, WHICH GENERATES A 3D IMAGE.
BARCODE READERS - A LASER SHINES ON A PATTERN OF BLACK BARS, THE REFLECTION IS RECORDED AND INTERPRETED AS A UNIQUE NUMBER IN A DATABASE OF ITEMS AND THE CORRECT PRODUCT DETAILS ARE RETURNED.
QR CODE READERS - A CAMERA DETECTS THE QR CODE WHICH IS A BUNCH OF BLACK SQUARES ARRANGED ON A WHITE BACKGROUND. THE PATTERN IS RECOGNISED, WHICH CAN THEN REDIRECT USERS TO CERTAIN INFORMATION OR REDIRECT THEM TO A WEBSITE.
DIGITAL CAMERAS - THEY CAPTURE IMAGES AND LIGHT FROM THE PLACE YOU WANT TO TAKE ENTERS THE CAMERA WHEN YOU PRESS THE BUTTON, AND ENTERS LIGHT DETECTORS (CHARGE-COUPLED DEVICE), WHICH SPLITS THEM UP INTO PIXELS, PRODUCING THE IMAGE.
KEYBOARDS - KEYS AND LETTERS ARE ARRANGED IN A SECTION, AND WHEN YOU PRESS ON A KEY, A CIRCUIT IS COMPLETED, WHICH SENDS A SIGNAL TO A PROCESSOR WHICH DETERMINES WHICH LETTER YOU PRESSED. (IT USES AN ASCII TABLE).
MICE - MODERN MICE TAKE LOADS OF SMALL RESOLUTION IMAGES AND CAN RECOGNISE PATTERNS ON THE SURFACE, SO IT CAN DETECT THE DIRECTION OF THE MICE MOVEMENT. OLD MICE USE A BALL, THE MOUSE TRACKS THE BALL MOVEMENT AND INTERPRETS THE MOVEMENT.
TOUCH SCREENS - IT HAS THREE DIFFERENT TYPES, RESISTIVE, CAPACITATIVE AND INFRA-RED. ALL THREE METHODS DETECT INPUT IN DIFFERENT WAYS.
INTERACTIVE WHITEBOARD - ESSENTIALLY THE SAME AS TOUCH SCREENS, EXCEPT ON A MUCH LARGER SCALE.
MICROPHONES - USED TO INPUT SOUNDS, THE SOUND IS DETECTED BY THE DIAPHRAGM AND AN ELECTRICAL SIGNAL IS TRANSMITTED TO THE COMPUTER. SPECIAL HARDWARE IS USED FOR ANALOGUE TO DIGITAL CONVERSION AND DATA CAN BE STORED AND/OR MANIPULATED.
 
DESCRIBE HOW THESE PRINCIPLES ARE APPLIED TO REAL-LIFE SCENARIOS, FOR EXAMPLE: SCANNING OF PASSPORTS AT AIRPORTS, BARCODE READERS AT SUPERMARKET CHECKOUTS, AND TOUCH SCREENS ON MOBILE DEVICES
SCANNERS MIGHT BE USED IN AIRPORTS OR FOR DOMESTIC USE. BARCODE SCANNERS FOR SUPERMARKET FAST CHECKOUTS, TOUCH SCREENS FOR ENTERING DATA IN PUBLIC PLACES OR FOR PHONE USAGE.
 
DESCRIBE HOW A RANGE OF SENSORS CAN BE USED TO INPUT DATA INTO A COMPUTER SYSTEM, INCLUDING LIGHT, TEMPERATURE, MAGNETIC FIELD, GAS, PRESSURE, MOISTURE, HUMIDITY, PH AND MOTION

MANY SENSORS SUCH AS LIGHT, TEMPERATURE, MAGNETIC FIELD, GAS, PRESSURE, MOISTURE, HUMIDITY, PH AND MOTION SENSORS MAY BE USED FOR DIFFERENT PURPOSES AND CAN BE INPUTTED INTO A COMPUTER SYSTEM. MOST OF THEM REQUIRE AN ADC (ANALOGUE TO DIGITAL CONVERTER) AS MOST OF THEM ARE REAL DATA, AND HAS TO BE CONVERTED TO DIGITAL DATA FOR THE COMPUTERS TO PROCESS. 
 
DESCRIBE HOW THESE SENSORS ARE USED IN REAL-LIFE SCENARIOS, FOR EXAMPLE: STREET LIGHTS, SECURITY DEVICES, POLLUTION CONTROL, GAMES, AND HOUSEHOLD AND INDUSTRIAL APPLICATIONS
LIGHT SENSORS MAY BE FOR STREET LIGHTS. TEMPERATURE SENSORS FOR FERMENTERS. MAGNETIC FIELD SENSORS FOR NUCLEAR REACTORS (INDUSTRIAL USES). PRESSURE SENSORS FOR GAS RELATED ACTIVITIES (INDUSTRIAL USES). MOISTURE FOR MEASURING GENERAL HUMIDITY. PH FOR AGRICULTURAL USE (SOIL AND FERTILISERS). MOTION SENSORS FOR BURGLAR ALARMS (DOMESTIC).

1.3.2 Computer architecture and the fetch-execute cycle

SHOW UNDERSTANDING OF THE BASIC VON NEUMANN MODEL FOR A COMPUTER SYSTEM AND THE STORED PROGRAM CONCEPT (PROGRAM INSTRUCTIONS AND DATA ARE STORED IN MAIN MEMORY AND INSTRUCTIONS ARE FETCHED AND EXECUTED ONE AFTER ANOTHER)
THE SIMPLE EXPLANATION IS, THAT DATA IS FETCHED IN THE CPU, MEANING THAT DATA IS TRANSFERRED INTO THE CPU FOR PROCESSING, THEN DECODED, WHICH IS WHEN THE CPU INTERPRETS THE DATA THAT IT HAD FETCHED AND MAKES IT READABLE FOR THE CPU. FINALLY THE EXECUTE CYCLE IS WHEN THE DATA WHICH IS FETCHED AND DECODED IS THEN EXECUTED, SO THE DATA’S INSTRUCTIONS ARE CARRIED OUT IN THIS STAGE.

DESCRIBE THE STAGES OF THE FETCH-EXECUTE CYCLE, INCLUDING THE USE OF REGISTERS
THE STEPS/PROCEDURE IS THE FOLLOWING:
FETCH
1. CONTENTS OF PC TRANSFERRED TO MAR VIA THE ADDRESS BUS
2. CONTENTS OF MEMORY AT THE LOCATION IN THE MAR TRANSFERRED TO MDR 3. CONTENTS OF MDR TRANSFERRED TO CIR
DECODE
1. CONTENTS OF CIR ARE DECODED BY THE CONTROL UNIT 2. CONTROL UNIT INCREMENTS THE PC BY ONE
EXECUTE
1. MEMORY ADDRESS TRANSFERRED TO MAR
2. DATA IN MAR LOCATION IS SENT TO MDR (AND PROBABLY TO THE ACCUMULATOR) 3. INSTRUCTION EXECUTE

1.3.1 Logic Gates

USE LOGIC GATES TO CREATE ELECTRONIC CIRCUITS +  
UNDERSTAND AND DEFINE THE FUNCTIONS OF NOT, AND, OR, NAND, NOR AND XOR (EOR) GATES, INCLUDING THE BINARY OUTPUT PRODUCED FROM ALL THE POSSIBLE BINARY INPUTS (ALL GATES, EXCEPT THE NOT GATE, WILL HAVE 2 INPUTS ONLY) + 
DRAW TRUTH TABLES AND RECOGNISE A LOGIC GATE FROM ITS TRUTH TABLE +
RECOGNISE AND USE THE FOLLOWING STANDARD SYMBOLS USED TO REPRESENT LOGIC GATES: NOT AND OR NAND NOR XOR +PRODUCE TRUTH TABLES FOR GIVEN LOGIC CIRCUITS

 

PRODUCE A LOGIC CIRCUIT TO SOLVE A GIVEN PROBLEM OR TO IMPLEMENT A GIVEN WRITTEN LOGIC STATEMENT, SUCH AS IF (SWITCH A IS NOT ON) OR (SWITCH B IS ON AND SWITCH C IS NOT ON) THEN ALARM, X, SOUNDS 
THIS IS WHEN A SCENARIO IS GIVEN, AND THE LOGIC GATES HAVE TO BE ARRANGED SO THAT THE CORRECT OPERATION IS CARRIED OUT.