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
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Computing Systems
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Hardware Components
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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
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But why use binary?
But why binary ?
Place Value Notation
Converting from Binary
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What are the decimal equivalents of:
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101
1111
10 0000
10 1010
Converting to Binary
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What are the binary equivalents of
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9
27
68
1000
UMBC Computing Environment
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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
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Lab 1 will walk you through using the UMBC
computing environment
How do I connect to GL?
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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
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See:
http://www.csee.umbc.edu/resources/computer-sciencehelp-center/#Resources
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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
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Can contain files and other directories
(calledsubdirectories)
/afs/umbc.edu/users/first/second/username/home
201
lab1
lab1.py
myOtherClass
HW1
- When you log into Gl,
you will be in your
home directory
- use the cd command to
go to subdirectories
emacs
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Reference:
http://www.csee.umbc.edu/summary-of-basic-emacs-commands/
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emacs – a text editor
◦ We will generally use emacs to write our python code
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To open a file that you want to call example.txt (replace
example.txt with your file name):
◦ Type: emacs example.txt
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To save a file:
◦ CTRL X and CTRL C
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To reopen the file:
◦ Type: emacs example.txt
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To remove the file
◦ Type: rm example.txt