Section 1 Flashcards
(46 cards)
What is hardware?
Any physical component that makes up a computer.
What is software?
Any program that runs on a computer.
What are the 4 basic components that all computers have?
Input device (e.g. mouse), CPU, Output device (e.g. speaker), Main memory
What is main memory also called?
RAM = main memory = primary storage = memory
What does secondary storage do?
It stores data that is used to perform processing, and data that is generated from processing input.
What is the main idea of the Von Neumann architecture?
Holding programs in addition to data in memory, allowing for data to move between the memory unit (main memory) and the processor (CPU).
What did the Von Neumann architecture improve?
Previously, programs were hardwired into the computer for specific tasks, and to change the program, you had to change the hardwire. With the Von Neumann architecture, you could change what a computer did by simply loading in a new programe, making it more general-purpose.
What does the CPU do?
It executes programs and manages the rest of the hardware in the computer.
It 1. stores and retrieves data, 2. processes information and 3. sends signals to different parts of the computer.
What is the fetch stage and which registers does it involve?
The CPU fetches an instruction from main memory.
- PC (holds memory address, increments after each stage)
- MAR (temporarily stores address of instruction/ data the CPU has to access)
- MDR (temporarily holds the instruction fetched from main memory)
What is the decode stage and which registers does it involve?
The (CU in the) CPU decodes the meaning of the fetched instruction and prepares to execute it.
- CIR (holds the instruction, not data, while the CU decodes it)
What is the execute stage and which registers does it involve?
The CPU executes the instruction.
- ACC (stores the results of calculations or operations)
- ALU (performs calculations and logical operations)
- could also involve MAR and MDR if instruction involves fetching from main memory, and could involve PC if the instruction involves a jump.
Which components are in a CPU?
CU, ALU and registers (very fast memory locations): MDR, MAR, PC, ACC
What is the function of the CU?
The CU coordinates all the activities taking place inside the CPU.
1. It controls the execution of instructions in the correct sequence.
2. It decodes instructions
3. It regulates and controls processor timing using regular pulses from the system clock
4. It sends and receives control signals to and from other devices within the computer.
What is the function of the ALU?
It carries out logical operations (and, or, not), shift operations (binary shifts) and arithmetic operations (+-*/)
What does the MAR do?
It holds the memory address of the instruction or piece of data to be fetched or stored.
What does the MDR do?
It holds data or a program instruction temporarily when it is fetched from memory or is to be sent to memory.
What does the PC do?
IT holds the memory address of the next instruction to be processed.
What does the ACC do?
It holds the results of operations carried out in the ALU.
What are the factors affecting a CPU’s performance?
Clock speed, cache size and number of cores.
What is clock speed?
How fast the CPU can process instructions. It’s measured in hertz (Hz), which tells you how many cycles (or ticks) the CPU can complete per second.
What bottlenecks could potentially slow the CPU down?
- slow RAM
- slow/ full HDD/ SSD
- slow cache
What is cache memory?
A storage area near the CPU that is very fast yet small and expensive, and allows the CPU to access data that is frequently used, which speeds up processor speed as the CPU does not have to access main memory as often.
What are the different levels of cache?
- Level 1 cache (extremely fast but small, 2-64KB)
- Level 2 cache (fairly fast and medium sized, 256KB-2MB)
- some CPUS have level 3 data cache
What is parallel processing?
A CPU having more than one core, so that two or four instructions can be executed simultaneously.
