Before the IC#

Before logic could be bought as a part, it had to be built from whatever could hold two distinguishable states: a relay that was open or closed, a tube that conducted or didn’t, a transistor that was on or off. Each of these represented a bit, and each came with its own penalties in size, power, heat, speed, and cost.

This part is the run-up to the integrated circuit. It matters because it explains why NAND gates became products — why it eventually made sense to etch thousands, then millions, of switches onto a single piece of silicon rather than wire them up by hand. The progression from discrete switching elements through the first scales of integration (SSI to VLSI) is the pressure that produced everything in the rest of the notebook.

Sections#

• Relays — Electromechanical switching: the first controllable logic element.
• Vacuum Tubes — Switching at electronic speed, at the cost of heat and fragility.
• Transistors — The solid-state switch that made everything after it possible.
• Why Integrated Circuits Happened — The economic and physical pressures that drove functionality onto silicon.
• SSI, MSI, LSI & VLSI — The scales of integration and what each made practical.