A computer is a programmable device that accepts input, processes information according to instructions, stores data and produces output. The most useful way to study computing foundations is to connect the vocabulary to something you have actually done on a phone or computer.
NOUN sources use both “Introduction to Computer Science” and “Introduction to Computers” as labels for CIT104 in different listings. This original companion focuses on broadly shared fundamentals and does not assert that every topic appears in every version.
What you will be able to do
- Explain the distinction between hardware and software
- Describe input, processing, storage and output using a concrete example
- Follow the logic of a simple algorithm
- Apply basic file-organisation and safe-computing practices
Lessons with worked examples
1. The computer as a system
A computer's behaviour comes from the interaction of hardware, software, data and the user. Hardware means physical components such as a keyboard, display or storage device. Software means instructions that direct hardware, such as an operating system, spreadsheet or browser.
A simplified information cycle is input → processing → output, often supported by storage. For example, when you type a course code into an exam timetable tool, the device accepts characters as input, software looks up matching information and the screen displays the matching entries.
- Classify parts by what they are rather than where they are located.
- Distinguish system software, which manages resources, from application software for tasks.
- Identify the stages in a familiar digital process.
Worked example — smartphone banking calculator
When you enter 1500 + 2700 into a calculator app, the touchscreen provides input, a processor executes the arithmetic instructions and the display shows 4200. The app is software; the display and chip are hardware. Saving the result would involve storage.
Takeaway: Computers accomplish tasks through interacting components, not a single magic “CPU process.”
2. Storage, memory and data organisation
RAM is working memory used for tasks currently being performed. Persistent storage retains files when the device is powered off. Confusing memory with storage leads to misleading statements about how a computer manages information.
Use clear filenames and directory structures. A file extension often suggests a format, but it does not prove that the content is safe or valid. If a file is critical, keep a backup in a trusted location and verify that you can open it.
- RAM is typically volatile; storage devices preserve information across power cycles.
- Backups protect against accidental deletion and device failure.
- A shared folder needs appropriate access controls.
Worked example — losing unsaved work
If you write notes in an application but have not saved them, unexpected shutdown may lose recent changes held only in volatile working state. Saving the document and maintaining a separate backup reduces that risk. Modern apps may autosave, but students should verify rather than assume.
Takeaway: A backup is useful only if it exists somewhere independently recoverable.
3. Algorithms: instructions that can be followed
An algorithm is an ordered set of steps designed to solve a problem. Good instructions are unambiguous and have a clear stopping condition. Algorithms can be expressed in plain language, flowcharts or pseudocode before being implemented in a programming language.
Test algorithms with representative cases: a normal input, a boundary case and an invalid input. A process that works for one example can still fail when a list is empty or an unexpected character appears.
- Define inputs, outputs and the condition that ends the process.
- Use decisions when a condition changes what should happen next.
- Test a small example by tracing the steps manually.
Worked example — pass threshold pseudocode
INPUT score. IF score is outside 0 to 100 THEN SHOW ‘Invalid score’. ELSE IF score ≥ 50 THEN SHOW ‘Threshold reached’. ELSE SHOW ‘Below threshold’. This is an illustrative algorithm, not a statement of NOUN's current grading policy.
Takeaway: Separating validation from the decision prevents invalid values being treated as legitimate scores.
4. Networks, online safety and basic digital literacy
Networks allow devices to exchange information. A website address, an account login and a stored PDF are different parts of the online experience. HTTPS helps protect information in transit, but it does not by itself prove that a website or a message is trustworthy.
Look for suspicious links and requests for credentials. Use unique passwords, keep recovery information secure and verify official portals before entering personal details. A file claimed to be a study document can still contain unsafe links or unexpected content.
- Verify domains rather than trusting a familiar logo.
- Avoid sharing passwords or session tokens in group messages.
- Download course files from trusted, authorised sources.
Worked example — recognising phishing
A message claims, ‘Your exam result is suspended; sign in now’, and links to a misspelled domain. The threatening tone, unusual domain and credential request are warning signs. Open the official site independently rather than clicking the message.
Takeaway: Security requires checking context as well as visible design.
Apply what you learned — CIT104 Practice Clinic
Original independent learning exercise. Try it before opening the worked explanation; this is not an official NOUN examination question.
Understand what survives a computer restart
Situation: A student types an assignment in an editor but has not saved it. They restart the laptop. The operating system and saved PDFs are still available, but the unsaved edits may be gone.
Your task: Explain the different roles of volatile working memory and persistent storage.
Reveal the step-by-step solution
- RAM generally holds active program data needed while software runs.
- Unsaved edits may remain only in volatile memory or temporary recovery files, depending on the application.
- Persistent storage such as an SSD normally retains saved files and installed software when power is off.
- Saving frequently and keeping a backup reduces the risk of losing important work.
Answer: RAM is usually volatile; SSD or disk storage is persistent. Saving moves work into an appropriate stored form, although application recovery features vary.
Common mistake to avoid: An editor’s autosave or recovery system is helpful but is not a substitute for verifying that the latest file was saved.
Test yourself — original practice questions
These are independently created learning questions, not official NOUN TMA or examination questions. Try each one before revealing the explanation.
Question 1. Which item is software?
- Keyboard
- Operating system
- Power cable
- Monitor
Show answer and explanation
Answer B: Operating system
An operating system is a set of instructions that manages computer resources.
Question 2. Which storage generally keeps files after power is turned off?
- CPU registers
- RAM alone
- Persistent SSD or disk
- Temporary processor cache
Show answer and explanation
Answer C: Persistent SSD or disk
Persistent storage is designed to retain data without power.
Question 3. What should an algorithm include?
- Only a title
- Clear input, steps and an end condition
- A paid subscription
- A different keyboard
Show answer and explanation
Answer B: Clear input, steps and an end condition
An algorithm needs understandable, terminating instructions.
Question 4. Why should a suspicious login link be verified?
- All secure connections are dishonest
- A convincing appearance does not prove a domain is legitimate
- A course code protects the website
- Screenshots guarantee authenticity
Show answer and explanation
Answer B: A convincing appearance does not prove a domain is legitimate
A forged message can imitate branding while sending credentials elsewhere.
Three things to practise this week
- Diagram input, processing, storage and output for a real task you perform.
- Write pseudocode that checks whether a list of course codes is empty before processing.
- Explain the difference between RAM and storage using two examples.
Continue learning on PsalmEduLabs
Look up CIT104 in the relevant tool. Course availability may vary; we do not expose PRO-only documents in these public lessons.
Verify the course with NOUN
Check your current official course material for assessment rules, units and session-specific instructions. Institutional pages below establish course identity and broad subject context; they are not citations for our original worked exercises.
Continue with a related course
Build on this topic using another free PsalmEduLabs learning guide.