Crash Course Digital Electronics

Explore the arithmetic logic unit (ALU), the computer's math brain, focusing on addition and basic operations built from AND, OR, NOT, and XOR gates, including the Intel 74181.

Explore the full-adder, which takes A, B, and C to produce sum and carry. Build it from two half-adders and an OR gate, then apply to multi-column addition.

Explore how an 8-bit ripple carry adder adds two numbers using half-adders and full adders, highlighting overflow, carry propagation, and the move to carry-lookahead adders for speed.

Explore how random access memory stores data while powered, and compare RAM with persistent memory. Build a one-bit storage circuit and begin forming a memory module for future CPU integration.

Create a memory element by looping back an or gate and an and gate, forming an and-or latch with set and reset inputs to write and read a single bit.

We introduce the central processing unit, show how it executes instructions via the alu and registers, and explain the 16-location 8-bit ram with opcodes and the instruction and address registers.

Execute the fetch–decode–execute cycle to run the program, with the control unit configuring RAM, registers A and B, and the ALU to perform add and store operations.

Discover how high clock speeds and expanding instruction sets create RAM bottlenecks, and how a cache on the CPU reduces data transfer delays to boost performance.

conditional jump instructions affect execution flow, causing stalls; speculative execution and branch prediction help keep pipes full and improve throughput, with superscalar CPUs delivering multiple instructions per cycle.

Examine superscalar processors that fetch and decode multiple instructions, execute in parallel using duplicate ALUs, and extend to multicore designs for parallel instruction streams.

Examine how early tabulating machines used plug boards to pass signals and how swappable boards enabled different programs, leading to memory-based stored programs and the Von Neumann architecture.

Examine how punch card readers load programming data into memory, process stacks of cards, and strip to maintain order, as Sage Air Defense System used 62,500 cards totaling five megabytes.

Panel programming used front-panel switches and indicator lights to enter and monitor memory, as seen with the Altair 8800, highlighting why early programming required hardware knowledge.

Explore how opcodes and memory addresses encode instructions to load data into register A. See an eight-bit instruction where 0010 means load into register A and 1110 designates address 14.

Explore how assemblers translate human-readable assembly language into native machine code, enabling direct hardware interaction, with labels and jump addresses that simplify programming and manage registers and memory.

Explore the evolution of programming languages from COBOL to modern high-level languages, and how compilers enable write once, run anywhere across different machines, lowering barriers to entry.