Computer Science Paper 1 Content

Computer Science Paper 1 Content

1. !.! The characteristics of contemporary processors, input, output and storage devices

   • 1.1.1 Structure and Function of the Processor
     • ALU, CU and Registers
       • ALU/Arithmetic Logic Unit -
     • ALU, CU, Registers and Buses
       • ALU/Arithmetic Logic Unit - Used To carry out basic arithmetic like binary addition and subtraction. Able to carry out some more complex mathematical functions such as sine cosine and floating point division
       • CU/Control Unit - uses control signals to coordinate units of the CPU to determine the flow of data, also used to decode data during the FDE cycle
       • Registers
         • PC - Address of next instruction to be executed
         • MAR - Address of memory location currently being used
         • MDR - Instructions or data to be executed
         • CIR - Holds instructions while it is decoded
         • ACC - Results of calculations processed by ALU
       • Buses
         • Data Bus - Data transmitted between CPU and memory, one at a time and both directions
         • Address - address of data sent with data, CPU only sends address to memory never the opposite
         • Control - CU sends signals and receives signals all of which travel across this bus, ensuring each process is carried out at the right time and order
     • Fetch, Decode, Execute
       • Fetch
         • 1. PC -> MAR
         • 2. PC + 1
         • 3. CU -> Fetch signal -> Control Bus -> RAM Address in MAR -> Address Bus -> RAM value in RAM -> Data Bus -> MDR
         • 4. MDR -> CIR
       • Decode
         • 1. CIR -> CU
       • Execute
         • instruction -> ALU to perform logical or mathematical functions on them
     • CPU Performance
       • Clock Speed
         • Faster clock speed - more clock cycles per second
       • Cache Memory
         • Larger cache - more previous instructions can be stored
       • Number of Cores
         • Doubling Cores != Doubling Speed
       • Pipelining - the process in which multiple processes can be processed concurrently
       • Processor Architectures
         • Von Neumann
           • Single CU, Single Address and Data Bus
           • Data and instructions stored in the same memory unit
           • Pipelining is unavailable
         • Harvard
           • Contemporary
             • Modified version of Harvard
           • Data and instructions in different memory units
           • Separate buses for data and instructions
           • Pipelining is available
             • Single clock cycle
   • 1.1.2 Types of Processor
     • RISC/Reduced Instruction Set Computing
       • Simple Instructions
       • Few Cycles per instruction
       • LMC
       • Emphasis on Software
       • Pipelining
       • Smartphones, Tablets due to simplicity
     • CISC/Complex Instruction Set Computing
       • Complex instructions
       • More clock cycles per instructions
       • Emphasis on Hardware
       • No pipelining
       • Desktop Computer due to complexity
     • Co-Processors
       • Specialized processors that work alongside the CPU
       • Improves processing speed by taking on other tasks to free up the load on the CPU
     • Parallel Processor
       • Multiple Independent processors work on one split up process where each processor take on one fraction of the overall process.
     • SIMD/Single Instruction Multiple Data
       • Parallel units share the same instruction but is carried out on separate sets of data
     • MIMD/Multiple Data Multiple Instructions
       • Parallel units each have their own separate instructions and each do something at any given time.
     • GPU
       • A type of specialist processor that is typically SIMD as the processes the GPU tends to take on are repetitive mathematical operations
   • 1.1.3 Input, Output and Storage
     • Input
       • Keyboard
       • Mouse
       • Webcam
     • Output
       • Screen
       • Speaker
       • Printer
     • Storage
       • Primary
         • RAM
           • Volatile - Content is wiped upon power off
           • Data is appended and deleted and added at any time
             • Read AND Write
           • Stores data currently being used
         • ROM
           • Non-Volatile - No data is lost upon power off
           • Stores BIOS
             • Basic Input Output System see 1.2.1 for more
               • Runs Power On Self Test
                 • Checks all devices that are connected work and BIOS is not corrupted
           • Read ONLY
         • Cache
           • High speed volatile memory
           • Frequently Accessed Data
         • Emulated Primary Storage
           • Used when primary memory is full
           • Virtual memory
       • Secondary
         • Magnetic
           • Magnetized Dots
           • Read/Write Head
           • Platter Head
           • Cheapest per Bit
           • Quick to access
           • Slower than SSD
           • Moving Parts
         • Flash/SSD
           • No moving Parts
           • Fast
           • Expensive
           • Uses different heights of transistors
         • Optical
           • Laser on spinning Disk
           • Pits and Lands
           • Cheap
           • Portable
           • Scratched make unreadable
           • Small amount of storage
           • Slow to Access Data
       • Virtual
         • Cloud
           • Abstracted view of a server in a distant location
           • Online Based
           • Control of own security

2. 1.2 Software and Software Development

   • 1.2.1 Systems Software
     • Operating Systems
       • Types Of OS
         • Multi Tasking
           • Multiple tasks can be carried out simultaneously
             • Anti Virus Scan while you use a word processor
           • Allows for working of more programs than cores
             • Switches attention between programs being used
         • Multi User
           • Allows the use between multiple accounts
           • Preferences are saved for each account
           • One single computer
         • Real Time
           • Input is processed quick enough to affect the next output
           • Can clearly communicate with the processor
           • Immediate response scenarios
             • Hospital
             • Nuclear Power Stations
           • Guaranteed to give output in a given time period
         • Distrbuted
           • Controls and coordinates multiple computer systems
           • Abstracted to seem as if they are one system
           • Multiple systems work on one task
         • Embedded
           • Single specialized task
           • Low powered CPU and RAM
           • TVs, Washing Machines etc.
           • Optimized for the task
           • Run faster as they are more simple than a general CPU
       • Features
         • Security
         • Utility
         • Network Management
         • Device Drivers
         • Error Reporting
         • Memory Management
           • Paging
             • Process is split into equal sized blocks
               • Pages
             • Processes may have excess storage that they don't require
           • Segmentation
             • Process is split into unequal sized blocks
               • Segments
               • Reflect on the logic of the Program
             • Less likely to have excess memory space
             • logical operations are kept together
           • Virtual Memory
             • When RAM is full
             • Area of the Hard Drive
             • Programs that have been inactive the longest are stored here
             • Loaded back into the RAM when needed
             • Allows to multi-task more/bigger programs than normal
         • Resource Management
         • Boot File
         • File Management
         • Input and Output Management
         • The Kernal
         • Device Management
         • User Interface
         • Interrupt Management
   • 1.2.4 Types of Programming Language
   • 1.2.2 Applications Generation
   • 1.2.3 Software Development

3. 1.3 Exchanging Data

   • 1.3.1 Compressing, Encryption and Hashing
   • 1.3.2 Databases
   • 1.3.3 Networks

4. 1.5 Legal, moral, cultural and ethical issues

   • 1.5.1 Computing Legeslation
   • 1.5.2 Moral and Ethical Issues

5. 1.4 Data Types, Data Structures and algorithms

   • 1.4.1 Data Types
   • 1.4.2 Data Structures
   • 1.4.3 Boolean Algebra