CS208 Introduction to Computer Systems
Wednesday, 3 January 2024

+ Hi!
- Welcome back
- Jeff Ondich; call me Jeff; Olin 301A; jondich
- Prefect: Kaitlyn Peterson

+ Today: jumping into C programming
- A few logistics
- Using Visual Studio Code & mantis.mathcs.carleton.edu
- character_counter.c

+ Very rough key questions for the course
- How do various types of data and instructions get stored?
- How do high-level language constructs (loops, functions, etc.) get
    translated into low-level language constructs that the
    hardware can execute directly?
- What's going on when I run a program?

+ Rough plan
- The C programming language, including pointers
- Data representation
    how are integers, real numbers, and characters stored in memory and on disk?
- x86_64 assembly language
    - what is the assembly layer mental model? what operations are available?
    - how do C structures get implemented in assembly language?
    - debugging assembly code with gdb (the "GNU debugger")
    - reverse engineering compiled code
    - buffer overflow attacks
- the process and threads models; how the OS supports multi-programming
    (and why it turns out to be painful)
- TCP/IP networking with the sockets model

+ Logistics
- Course website
- Upper-right menu on course website
    - Info (general information about the course)
    - Resources
    - SAMPLES  <---------- !!!!
    - Office Hours
    - Jeff (my Carleton home page)
- Moodle: homework submission and quizzes
- Slack (#announcements, #questions, #random)
- VS Code, mantis, remote editing, integrated Unix terminal
- Online textbook: Dive into Systems
- First 3 weeks: five C programming assignments of increasing complexity
- End of week 4: in-class exam on C and data representation

+ hello.c
- go to the samples page in a browser
- connect to mantis
- create hello.c and copy the code over
- g++ -g -Wall -Werror -o hello hello.c
- ./hello

+ args.c
- what's going on here?

+ character_counter.c [Didn't get here in class today]
- how do you open a file? close a file?
- how do you read one char from a file?
- how can you tell if you have come to the end of the file?
- how can you tell if you have come to the end of a line?
- what other errors can happen, and what should you do about them?

+ Coming up next
- Lots more C and Unix
- Integer notations: binary (0b), octal (0), decimal, hexadecimal (0x)
- Data representation: integers, characters, real numbers, strings