CS208 Introduction to Computer Systems
Monday, 29 September 2025

+ Homework debrief
- Grace period: resubmission (if you want) through
Wednesday night (10/1)
- Major issues
    - Testing
    - 0xffffffc3
    - 

+ args.c

+ Try this

    char ch1 = 0x41;
    printf("ch1 = 0x%x\n", ch1);

    char ch2 = 0xC3;
    printf("ch2 = 0x%x\n", ch2);

+ What have we done so far?
- bits, bytes
- integer writing systems: decimal, binary, hexadecimal, octal
- bitwise operations in C
- fixed-size integers
    - C's int with gcc on mantis is 4 bytes / 32 bits
    - two's complement
        - how to recognize negative ints
        - how to negate an int (i.e., what's the
            2's comp representation of -x if x is an int?)
        - addition works normally!
        - ...but, you only have 32 bits, so problems can occur 
            [to be continued]
- C's char type
- byte order for ints
    - little-endian (what Intel and Apple Silicon use)
    - big-endian (what most people find easier to read (so sad))
- ASCII
- Unicode & codepoints
- Encodings of Unicode codepoints
    - UTF-16LE
    - UTF-16BE
    - UTF-8
    - BOM (byte order mark)
- The basic idea of memory
    - addresses
    - "char *" as a parameter type

+ This week
- More C
    - catch-up
    - command-line arguments
    - struct
    - pointers
    - pointer syntax: &, *, **, [], ->
    - arrays, pointer variables, literals, etc.
    - string library functions
    - ...
- Thinking more about memory