Coding Bootcamp: The life of a "Like"

Transistors and gates

• Transistor: a miniature switch
  
• Logic gate: digital building block

A NAND gate as transistors

By JustinForce - Own work, CC BY-SA 3.0

Digits and counting

• Counting with 0 and 1
  
• How to add two bits
  
• How to add three bits
  
• How to add 64 bits with 64 bits

A half adder

A full adder

A four bit adder

By Cburnett - Own work, CC BY-SA 3.0

A four bit ALU

By Poil - Own work, CC BY-SA 3.0

Information representation: positive integers

• 0000: 0
  
• 0001: 1
  
• 0010: 2
  
• 0011: 3
  
• 0100: 4
  
• 0101: 5
  
• 0110: 6
  
• 0111: 7

Information representation: negative integers

• 1111: -1
  
• 1110: -2
  
• 1101: -3
  
• 1100: -4
  
• 1011: -5
  
• 1010: -6
  
• 1001: -7
  
• 1000: -8

Information representation: letters

• 00100001: !
  
• 00111111: ?
  
• 00110000: 0
  
• 00111001: 9
  
• 01000001: A
  
• 01000010: B
  
• 01011010: Z
  
• 01100001: a
  
• 01100011: b
  
• 01111010: z

Information representation: floating point numbers

• 1: 0 01111111 [1]00000000000000000000000
  
• 1 × 1 × 2^{127 - 127}
  
• 2: 0 10000000 [1]00000000000000000000000
  
• 1 × 1 × 2^{128 - 127}
  
• 3: 0 10000000 [1]10000000000000000000000
  
• 1 × 1.5 × 2^{128 - 127}
  
• -1: 1 01111111 [1]00000000000000000000000
  
• -1 × 1 × 2^{127 - 127}

Information representation: floating point numbers

• 1.5: 0 01111111 [1]10000000000000000000000
  
• 1 × 1.5 × 2^{127 - 127}
  
• 1.1: 0 01111111 [1]00011001100110011001101
  
• 1 × 1.100000023841858 × 2^{127 - 127}
  
• 1.10000002384185791015625
  
• 2 × 10³⁰: 0 11100011 10010011111001011001010
  
• 1 × 1.5777218341827393 × 2^{227 - 127}
  
• 2000000030094932439753377710080

Ranges

• Integers
  
• 8-bit (byte): -128 to 127 or 0 to 255
  
• 16-bit (short): -32768 to 32767 or 0 to 65535
  
• 32-bit (int): ± 2 bn or 0 to 4 bn
  
• 64-bit (long): ± 10¹⁹
  
• Floating point numbers
  
• 32-bit (float/Single): ± 1.2 × 10^-38 to ± 3.4 × 10³⁸
  
• (6 decimal digits)
  
• 64-bit (double/Double): ± 2.2 × 10^-308 to ± 1.8 × 10³⁰⁸
  
• (15 decimal digits)

Chips and chip construction

• Gates are put together in integrated circuits
  
• Chips can serve various functions, such as CPU, memory, or interface
  
• Early ICs contained 2-6 gates (8-30 transistors)
  
• A modern CPU can contain 20 billion transistors

A NAND gate in CMOS

By Jamesm76 at English Wikipedia, Public Domain

Structure of a chip

By Cepheiden - self made, CC BY 2.5

A gate in three dimensions

By David Carron at English Wikipedia, Public Domain

A chip in a DIL package

By Zephyris at English Wikipedia - CC BY-SA 3.0

A peek through the window

By Zephyris at English Wikipedia - CC BY-SA 3.0

Flash memory through electron microscopy

By Micron Technology Inc.

Inside a modern computer

• CPU
  
• RAM
  
• Secondary storage (magnetic disk, SSD)
  
• ROM
  
• Interfaces
  
• USB
  
• DMA
  
• Networking
  
• Graphics

Low-level programming

• Registers
  
• Arithmetic instructions
  
• Control flow
  
• Memory access
  
• Stack

High-level programming

• Compiling expressions into instructions
  
• Interpreting instructions
  
• Tokens
  
• Constants
  
• Operators
  
• Reserved words
  
• Comments
  
• Syntax

Commonly used programming languages

• C
  
• C++, Go, Rust
  
• Java, C#, Swift
  
• JavaScript, PHP
  
• Python, Ruby, Perl

Memory organization

• Code
  
• Stack
  
• Heap
  
• Constants

Operating system

• Process isolation
  
• Device virtualization
  
• Multitasking
  
• Application host
  
• System calls (API)

Network layers

• Application
  
• Presentation
  
• Session
  
• Transport
  
• Network
  
• Link
  
• Physical

Building the web

• HTML
  
• HTTP
  
• DNS
  
• TCP
  
• IP

Trace of a DNS query

Anatomy of a captured network packet

A trace of a packet's route

Serving requests

• Data centers
  
• Load balancing
  
• Application servers
  
• Databases
  
• Microservice architectures