Lecture 2: Computing Basics

Brian J. Smith

2026-01-20

Computing Basics

Basic Computer Operations

flowchart LR
 subgraph B["Process"]
        RAM["RAM"]
        CPU["CPU"]
        HDD["HDD"]
  end
    CPU <--> RAM & HDD
    A["Inputs"] --> B
    B --> C["Outputs"]

Figure 1: A very simplified diagram of a computer.

What’s the difference between Random Access Memory (RAM) and a hard disk drive (HDD)?

Operating Systems

What does an operating system do?

What are some example operating systems?

Operating Systems

Windows
Unix-like
- macOS
- (iOS)
- Linux
- (Android)

Operating Systems

	Windows	Unix
CLI	`cmd.exe`	`bash`
Directory separator	`\`	`/`
Root directory	`C:\`	`~/`

File Structure

Hierarchical databases

Example file structure

File structure

Absolute vs. relative paths

What’s the difference between an absolute and relative path?

When should you use each one?

File structure

Absolute path:

C:/Users/bsmith/Teaching/UI 2026-01 Spring/BCB5200/BCB5200_Website/lectures/01_intro.qmd

Relative path:

./lectures/01_intro.qmd

File structure

Relative paths

. points to the current directory

.. points to the parent directory

File structure

|---C:/
|---|---Users/
|---|---|---bsmith/
|---|---|---|---Documents/
|---|---|---|---|---Website/
|---|---|---|---|---|---index.html
|---|---|---|---|---|---img/
|---|---|---|---|---|---|---img1.png
|---|---|---|---|---|---|---img2.png
|---|---|---|---Pictures/
|---|---|---|---|---img3.png

From index.html:

How do I get to img1?
- C:/Users/bsmith/Documents/Website/img/img1.png
- img/img1.png
- ./img/img1.png

File structure

|---C:/
|---|---Users/
|---|---|---bsmith/
|---|---|---|---Documents/
|---|---|---|---|---Website/
|---|---|---|---|---|---index.html
|---|---|---|---|---|---img/
|---|---|---|---|---|---|---img1.png
|---|---|---|---|---|---|---img2.png
|---|---|---|---Pictures/
|---|---|---|---|---img3.png

From index.html:

How do I get to img2?
- img/img2.png

File structure

|---C:/
|---|---Users/
|---|---|---bsmith/
|---|---|---|---Documents/
|---|---|---|---|---Website/
|---|---|---|---|---|---index.html
|---|---|---|---|---|---img/
|---|---|---|---|---|---|---img1.png
|---|---|---|---|---|---|---img2.png
|---|---|---|---Pictures/
|---|---|---|---|---img3.png

From index.html: