CS208 Introduction to Computer Systems
Friday, 26 September 2025

+ Thanks for the LLM.txt

+ Questions?

+ Memory, char *, etc.

+ Byte order
- What's the problem?
- "byte order" = "endianness"
- "Gulliver's Travels" and "On Holy Wars & a Plea For Peace"
- Bits are bits; context determines meaning
- Intel x86_64 architecture (mantis & most Windows computers)
     uses little-endian; therefore, so will we

+ UTF-16LE, UTF-16BE, and UTF-8

+ Bit operations
- Turning individual bits on and off

    0110 0101 = x
  & 1101 1111 = mask     --> turns off the 3rd bit from the left in x
                        build the mask: mask = ~(0x20)

    0100 0101 = x
  | 0010 0000 = mask      --> turns on the 3rd bit from the left

Interpret those examples as x == an ASCII character

    0110 0101 == 'e'
  & 1101 1111
    ---------
    0100 0101 == 'E'

- Masking

    0110 0101
  & 0000 1111