1. Computing Fundamenatls CMSC 201 Computer Science I Penny Rheingans University of Maryland Baltimore County (with inspiration from previous 201 instructors and the creators of UMBC’s CMSC 101 and HMC’s CS5)

2. Learning Objectives
To have a very basic overview of the components of a computer system
To understand how data is represented and stored in memory
To be aware of elements of the UMBC computing environment

3. Computing Systems Hardware Components Software Components
Central Processing Unit (CPU)
Auxiliary Processors (GPU, etc)
Memory
Bus
Network Connection
External Devices: keyboard, monitor, printer
Software Components
Operating System: Linux, MacOS, Windows, etc
Applications

4. Binary Representation
All information is store in a binary representation (ie, it’s all 1s and 0s): code, text, images, sounds
For each type of item/object, there are specific formats that define who to represent that thing (character, digit, sound, image, etc) in binary
But why use binary?

6. But why binary ?

7. Place Value Notation

8. Converting from Binary
What are the decimal equivalents of:
101
1111
100000
101010
101 = 5
1111 = 15
= 32
= 42

9. Converting to Binary What are the binary equivalents of 9 27 68 1000
9 = 1001
27 = 11011
68 =
1000=

10. UMBC Computing Environment
We will develop our programs using UMBC’s GL system
GL is running the Linux Operating System
GUI interface – Graphical user interface
Command-Line Interface – When you connect to GL using SSH
Lab 1 will walk you through using the UMBC computing environment

11. How do I connect to GL? Assuming you have Internet access, use SSH
Windows
Download Putty (Lab has a video about this)
Hostname – gl.umbc.edu
Make sure you pick SSH
Put in username and password
Mac
SSH client already installed
Go to the Application folder and select Utilities
Open up a terminal Window
Type ssh -l username gl.umbc.edu
Put in your password

12. Linux Commands See: For now, let’s just learn:
help-center/#Resources
For now, let’s just learn:
ls – list
Display the files and directories in your current directory
cd – change directory
Directory is another word for folder
.. = parent directory
. = current directory
mkdir- make directory
Note: Commands are case-sensitive

13. Directories
Can contain files and other directories (calledsubdirectories)
/afs/umbc.edu/users/first/second/username/home
201
myOtherClass
lab1
When you log into Gl, you will be in your home directory
use the cd command to go to subdirectories
HW1
lab1.py

14. emacs Reference: emacs – a text editor
emacs – a text editor
We will generally use emacs to write our python code
To open a file that you want to call example.txt (replace example.txt with your file name):
Type: emacs example.txt
To save a file:
CTRL X and CTRL C
To reopen the file:
To remove the file
Type: rm example.txt