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)

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

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

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?

But why binary ?

Place Value Notation

Converting from Binary What are the decimal equivalents of: ◦ 101 ◦ 1111 ◦ ◦

Converting to Binary What are the binary equivalents of ◦9◦9 ◦ 27 ◦ 68 ◦ 1000

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

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

Linux Commands See: 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

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

emacs Reference: 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: ◦ Type: emacs example.txt To remove the file ◦ Type: rm example.txt