Computing Basics and Digital Literacy

Week of 2026-08-25 · Download .docx

Objectives

Explain how computers use the IPO model to process, store, and output data, and identify the role of the CPU, RAM, and storage.
Convert numbers between binary, decimal, and hexadecimal and explain how computers represent text, images, and audio as binary data.
Identify common input, output, and peripheral devices and describe the data flow direction for each.
Apply ethical standards and acceptable use policies when accessing digital resources and explain software licensing categories.

Key terms

IPO Model: Input → Processing → Output: the three-step model describing how a computer receives data, processes it, and delivers results.
CPU: Central Processing Unit — the primary chip that fetches, decodes, and executes instructions. Measured in GHz (clock speed) and core count.
RAM: Random Access Memory — volatile, high-speed storage for programs and data currently in use. Contents are erased on power loss.
ROM: Read-Only Memory — non-volatile chip holding firmware (BIOS/UEFI). Retains data without power.
Bit: The smallest unit of digital information — a single binary digit (0 or 1) representing one electrical state.
Byte: Eight bits grouped together. One byte can represent 256 distinct values (2⁸) and typically encodes one character.
Binary: Base-2 number system using only 0 and 1. All computer data is ultimately stored in binary form.
Hexadecimal: Base-16 number system using digits 0–9 and letters A–F. One hex digit represents four bits (a nibble).
ASCII: American Standard Code for Information Interchange — a 7-bit character encoding standard mapping numbers 0–127 to printable characters and control codes.
UTF-8: Variable-width Unicode encoding (1–4 bytes per character) that can represent every character in every human language and is backward-compatible with ASCII.
Input Device: Hardware that captures data from the user or environment and sends it to the computer (keyboard, mouse, microphone, scanner).
Output Device: Hardware that receives processed data from the computer and delivers it to the user (monitor, printer, speaker).
AUP: Acceptable Use Policy — organizational document defining permitted and prohibited uses of IT resources.
Open Source: Software distributed with source code under a license permitting viewing, modification, and redistribution (e.g., GPL, MIT, Apache).
Copyleft: A licensing requirement (used in the GPL) that derivative works must also be distributed under the same open-source license.

The concept

Computers are information machines. Everything they do — from displaying a webpage to running a video game — follows the same three-step cycle: Input, Processing, Output. Understanding this IPO model is the foundation of all IT knowledge.

**How Computers Think in Binary**

At the hardware level, a computer is made of billions of tiny switches called transistors that can be either on (1) or off (0). This two-state system is called binary. Because hardware can reliably detect two electrical states, all computer data — numbers, letters, images, audio, video — is ultimately encoded as sequences of 0s and 1s.

Eight bits grouped together form a byte. A byte can represent 256 distinct values (2 to the power of 8 = 256), which is enough to encode a single character using ASCII, one audio sample, or one color channel in a pixel. Modern computers work with kilobytes (1,024 bytes), megabytes (1,024 KB), gigabytes (1,024 MB), terabytes (1,024 GB), and beyond.

**Number Systems**

Binary (base-2) uses positional notation just like decimal (base-10), but each position represents a power of 2 instead of 10. Binary 1000 = 1×2³ = 8 in decimal. Binary 1101 = 8+4+0+1 = 13.

Hexadecimal (base-16) is a compact way to write binary — one hex digit represents exactly four bits. Hex is used for memory addresses, color codes (#FF5733), and MAC addresses because it is far shorter than the equivalent binary string.

**Representing Data**

Text is encoded using character encoding standards. ASCII assigns numbers 0–127 to English characters and control codes. Unicode (with UTF-8 encoding) extends this to every character in every language using 1–4 bytes per character.

Images are represented as grids of pixels, each pixel storing its color as three 8-bit values for red, green, and blue (RGB). A 1920×1080 image has over two million pixels. Audio is represented by sampling the sound wave thousands of times per second (44,100 samples per second for CD quality) and encoding each sample's amplitude as a binary number.

**The CPU and Memory**

The CPU (Central Processing Unit) is the brain of the computer. It executes the fetch-decode-execute cycle continuously: fetch an instruction from RAM, decode what operation is required, execute it. CPU performance is measured by clock speed (GHz) — cycles per second — and core count — how many independent execution units are on the chip.

RAM (Random Access Memory) holds the programs and data currently in use. RAM is volatile, meaning it requires constant power to maintain its stored data — everything in RAM is lost when the computer is turned off. Storage (SSDs, HDDs) is non-volatile and retains data without power.

**Digital Ethics**

Being a digital citizen means using technology responsibly: respecting others' privacy, using licensed software correctly, creating strong passwords, protecting your personal information, and following your organization's Acceptable Use Policy.

Worked examples

Example 1: Binary-to-decimal conversion: Convert binary 1011 to decimal. Identify each bit's positional value from right to left: 2⁰=1, 2¹=2, 2²=4, 2³=8. Multiply each bit by its position value: 1×8 + 0×4 + 1×2 + 1×1 = 8+0+2+1 = 11. Answer: binary 1011 = decimal 11. Check: count the set bits — positions 3, 1, and 0 are set (8+2+1=11). ✓

Example 2: Identifying input vs. output: A student types a report (keyboard = input), the word processor formats it (CPU processing), and it prints on paper (printer = output). A touchscreen serves dual roles — it displays the UI (output) and detects touch gestures (input) — making it an I/O device. For every device you encounter, ask: which direction does data flow? Into the computer = input. Out of the computer = output. Both = I/O.

Common mistakes

Confusing volatile RAM with non-volatile storage. RAM loses data on power off. SSDs and HDDs keep data. When your computer crashes before you save, you lose unsaved RAM content — the saved copy on the SSD is intact.
Mixing up the storage units. The order is: bit → byte → KB → MB → GB → TB → PB. Each step multiplies by 1,024 (or 1,000 in some marketing contexts). 1 GB ≠ 1,000 MB exactly in binary measurement.
Thinking hexadecimal is a separate encoding. Hex is just a shorthand for binary — each hex digit represents exactly 4 bits. Hex A = binary 1010. Hex FF = binary 11111111 = decimal 255.
Assuming HTTPS means a website is safe and legitimate. HTTPS encrypts the connection — it cannot verify that the website owner is trustworthy. Phishing sites commonly have valid TLS certificates.
Calling the GPL and MIT licenses the same because both are open source. GPL is copyleft — any derivative must also be GPL. MIT is permissive — derivatives can be proprietary. This matters for commercial software decisions.

Self-check

Try each question before reading the answer. Answers at the bottom of this page.

1. What does the 'P' stand for in the IPO model?

Processing
Protocol
Peripheral
Program

2. How many bits are in one byte?

3. What is the decimal value of binary 1010?

4. Which type of memory loses all data when the computer is turned off?

5. A microphone is best classified as:

Output only
Storage device
Input device
I/O device

Self-check answers

1. A — Processing — the CPU processes input data to produce output.
2. B — 8 bits form one byte, which can represent 256 distinct values.
3. B — 1×2³ + 0×2² + 1×2¹ + 0×2⁰ = 8+0+2+0 = 10.
4. D — RAM is volatile — it requires constant power to retain data.
5. C — A microphone captures sound and sends it into the computer — data flows inward, making it an input device.

Canvas is the official record. This companion enhances the PGCC curriculum; it does not replace it. Last name and class year only. Students with a 504 plan or IEP: your accommodations apply.

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