- Relays, vacuum tubes, transistors.
Relay. Use electrically controlled mechanical switches. The control wire is connected to an intermediate coil, and the current generates a magnetic field through the intermediate coil, attracts the metal arm to close, and generates a path. Others can be connected, such as motors.
Vacuum tube. Seal the two electrodes of the glass tube, heating one end of the electrode will emit positive charges, and the other end will attract these positive charges to form a path. If a negative charge is emitted, it will not attract and cannot form a path.
Introducing a control level and applying a positive charge to the control electrode will allow electrons to pass through. If a negative charge is applied, the passage of electrons is blocked. Thereby connecting or disconnecting the circuit.
Giant computer, the first programmable computer. Just plug some wires into the electric board when programming. The emergence of vacuum tubes has driven computers from electromechanical to electronic drives.
Transistor. The two electrical levels are separated by a material, which is sometimes conductive and sometimes non-conductive, called a semiconductor. Introducing a control line, connecting a gate electrode, and changing the charge of the gate electrode can control the conductivity of the semiconductor material. Control pathways are formed.
- Boolean operation, binary? Half adder, full adder, ALU?
Use transistors to construct NOT, AND, OR, XOR, logic gate circuits. Complete basic true and false calculations. There are only two values, 0 and 1, and more digits are represented by increasing the number of digits.
A XOR logic gate and an AND logic gate are used to construct a half adder.
The three numbers A, B, and C are added together. A and B use a half adder, with output bits and carry two pins. The output bit and C then construct a half adder, with a new output bit, carry. The output bit is the final output bit. The carry and the carry of the first half adder form an OR gate to construct the final carry.
The ALU is composed of arithmetic operators and logical operators. The arithmetic operator implements multi-digit addition.