Exam (elaborations)
OCR Computer Science Paper 1 Set
- Course
- Institution
OCR Computer Science Paper 1 Set OCR Computer Science Paper 1 Set OCR Computer Science Paper 1 Set
[Show more]
Content preview
OCR Computer Science Paper 1 SetBasic computer system model - ANS Input, Processing, Output and optional storage
CPU - ANS Central Processing Unit
Input device - ANS A device used to enter information into a computer.
Output device - ANS any device that presents data from the computer
Storage device - ANS a piece of computer equipment on which information can be stored.
Central Processing Unit - ANS the part of a computer that decodes and executes instructions and
manages the rest of the hardware.
Von Neumann Architecture - ANS Instructions are fetched, decoded and executed one at a time.
Instructions and data are held together in the same memory space.
Bus - ANS The paths, or lines, on the motherboard on which data, instructions, and electrical power
move from component to component.
Address Bus - ANS carries addresses from the processor to memory and input/output devices.
Data Bus - ANS sends data between the processor, memory and input/output devices.
Control Bus - ANS carries signals to coordinate all the computer activities.
,CU - ANS Control Unit. Coordinates all the activities taking place inside the CPU.
Control Unit functions - ANS 1. controls the execution of instructions in the correct sequence.
2. decodes the instructions.
3. regulates and controls processor timing using regular pulses from the system clock.
4. sends and receives control signals to and from other devices within the computer.
ALU - ANS Arithmetic Logic Unit. Carries out all mathematical and logical operations.
Arithmetic Logic Unit functions - ANS 1. Logical Operations: AND, OR and NOT.
2. Shift Operations: The bits in a binary number can be shifted to the left or the right a number of times.
3. Arithmetic Operations: addition, subtraction, multiplication and division.
Special Purpose registers - ANS special very fast memory locations within the CPU with specific purposes
in the process of executing instructions.
MAR - ANS Memory Address Register
MDR - ANS Memory Data Register
PC - ANS Program Counter
ACC - ANS Accumulator
Memory Data Register (MDR) - ANS Holds the data fetched from or to be written to memory.
, Memory Address Register (MAR) - ANS Holds the address of data ready for use by the MDR, or the
address of an instruction passed from the PC.
Program Counter (PC) - ANS The register that contains the address of the next instruction to be
executed
Accumulator (ACC) - ANS Holds the result of calculations.
FDE Cycle - ANS Fetch Decode Execute Cycle. The CPU uses the FDE cycle to carry out the program
instructions.
Fetch - ANS 1. The address A of the next instruction to be executed is copied from the PC to the MAR
2. The PC is incremented so it points at the next instruction to be fetched. Simultaneously, the
instruction held in location A is then copied into the MDR.
3. The contents of the MDR are copied to the CIR.
Decode - ANS The CU decodes the instruction in the CIR to see what is to be done next.
Execute - ANS The instruction is executed.
Cache - ANS Memory in the processor providing fast access to frequently used instructions and data.
Factors affecting the speed of the CPU - ANS 1. Clock Speed
2. Number of Cores
3. Cache Size
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller lectjoseph. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $12.99. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
79373 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now