Building Larger Circuits

4-bit ALU

A 4-bit ALU that performs add, subtract, and, or, and xor selected by a 3-bit opcode, with carry-out and zero flags.

Traffic Light Controller

A 3-state, timer-driven Moore FSM that cycles a traffic light through red, green, and yellow with different hold times.

Simple Datapath: Register File + ALU + Writeback

Combine a register-file read, a combinational ALU, and a synchronous writeback into a one-instruction-slot datapath.

UART-Lite Transmitter

Shift a byte out serially as a UART frame (start bit, 8 data bits LSB-first, stop bit) driven by an external baud tick pulse.

Three-Request Priority Arbiter

Implement a synchronous three-device arbiter that chooses the highest-priority pending request and holds the grant until that request drops.

Counter with Period 1000

Generate a pulse at a period of exactly 1000 input clock cycles.

4-Bit Shift Register and Down Counter

Combine a loadable shift register with a decrementing count of remaining bits.

FSM: Sequence 1101 Recognizer

Detect the bit pattern 1101 in a serial stream, including overlapping matches.

FSM: Enable Shift Register

Control a serial shift register with a synchronous reset and enable.

The Complete Timer

Compose seconds and minutes counters with a rollover event.

FSM: One-Hot Logic Equations

Write Boolean next-state equations for a one-hot sequence detector.

FSM: The Complete FSM

Implement a complete Moore sequence detector with state and output visibility.