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Intro to Computer Science

Unit 1

Computing Systems

5 topics · 21 practice questions · Free responseNot yet reviewed

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Notes

Hardware and software

  • Hardware is the physical parts: CPU (runs instructions), RAM (fast, temporary memory), storage (SSD or HDD for long-term files), motherboard (connects parts) and GPU (graphics).
  • Software is the instructions. The operating system manages hardware, memory, files and the user interface. Application software helps users do tasks. Drivers let the OS talk to devices.

Input, process, output

  • Input devices (keyboard, mouse, microphone, camera) send data in. Output devices (monitor, speakers, printer) present results.
  • Computing follows input, process, output, with storage keeping data for later.

Memory and data

  • RAM is volatile (loses data without power); storage is non-volatile. SSDs are faster than HDDs.
  • Everything is stored as bits (1s and 0s). A byte is 8 bits. Units grow by about 1,000: KB, MB, GB, TB.
  • The CPU repeats fetch, decode, execute. Clock speed (GHz) and the number of cores affect performance.

Topics in this unit

Each topic has its own short notes and practice.

Practice

Which part of a computer permanently keeps your files when the power is off?
Which software manages memory, files and hardware for all other programs?
Which list contains only output devices?
A computer has 8 GB of RAM and a 512 GB SSD. What is true?
How many bits are in 3 bytes?
A user installs a game and it runs slowly because the computer keeps waiting on data. Which change would most likely help?

Free response

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Free-response question

A student is choosing a laptop for schoolwork and video editing.

(a) Name the component that runs program instructions and the component that holds the programs and files currently in use.

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The CPU runs the instructions. The RAM holds the programs and data currently in use.

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(b) Explain the difference between RAM and an SSD, including what happens to each when the laptop is shut down.

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RAM is fast, temporary and volatile, so it is emptied when power is off. An SSD is slower but non-volatile, so the files stay saved.

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(c) The student plugs in a new webcam and a microphone. Classify each as input or output and explain what the operating system needs to make them work.

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Both are input devices. The operating system needs a driver for each device so it can communicate with it.

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