History: a computer from the catalogue

1964 — the 54/74 series. Texas Instruments released chips in which several gates sit in one package with pins. The 54 series was made for the military, the 74 series — cheap, in plastic — for everyone. The number told what was inside: 7400 — four NANDs, 7474 — two flip-flops, 7490 — a decade counter. Soon the same chips with the same numbers were made by dozens of factories around the world.

74HC00N 2219pin 1pins — 2.54 mm apart, right for a breadboardthe notch and the dot —pins are counted from here
This is what a real 74HC00 looks like: a black plastic DIP-14 package the size of a fingernail — 19 × 6 mm, seven pins on each side. On top — the number and the batch code. Inside — a die with the same 16 transistors we build in lesson 1.
54/74 series1964Texas Instruments,gates in a packagePong1972a game withno processorApple I1976a processor +dozens of 74xx74HC1980sCMOS:low powerArduinotoday74HC595 —8 LEDsthe numbers stay: today's 74HC00 is the 7400 of the 1960s, only in CMOS
Sixty years of the 74 series: from the first packages with gates to an Arduino board. The technology changes, the numbers and pins stay.

1972 — a game without a processor. The first arcade machines, such as Pong, were built from 74-series chips with no processor: raster counters, comparison, flip-flops — all in hardware. Exactly what we did in "A Watch and a Game from Gates", only from packages.

1976 — the Apple I. Steve Wozniak loved to count chips: the fewer packages, the more beautiful the circuit. The Apple I had a 6502 processor, and everything around it — memory, video, keyboard — was made of a few dozen 74-series chips. Wozniak knew in advance what was inside each one and designed straight from the catalogue.

74HC04U174HC74U2VCCCLRCLKGNDJ1R2D2R1D1light tracks are on top, the dark dotted ones underneath; they change sides through a pin holethe square pad is pin 1; some tracks hide under the packagesJ1: power, CLR — reset, CLK — clock; D1 blinks at half the clock (÷2), D2 at a quarter (÷4)
A real board with two chips — half of the lesson 2 divider. The 74HC04 (U1) inverts the reset, the 74HC74 (U2) divides the clock. Every track runs from pin to pin: 1QN goes to 1D and to the clock of the second flip-flop, 2QN to 2D, nCLR to both resets; the free inputs of the 74HC04 go to ground. Some tracks run under the package, between the rows of pins.

1980s — 74HC. The first 74-series chips used bipolar transistors (TTL) and got noticeably warm. The HC family is CMOS: the same numbers, the same pins, and pairs of P and N transistors inside, as in our gates. They draw current only when they switch.

Today. The 74HC00 and 74HC74 are still made. The 74HC595 sits on thousands of Arduino boards: three wires from the controller — and eight LEDs. We build exactly the 74HC: inside, each one works the same way as in our simulator.