We use a microcontroller without a second thought, in applications where once we might have resorted to a brace of 74 logic chips. But how many of us have spared a thought for how the microcontroller evolved? It’s time to go back a few decades to look at the first commercially available microcontroller, the Texas Instruments TMS1000.
Imagine A World Without Microcontrollers
It’s fair to say that without microcontrollers, many of the projects we feature on Hackaday would never be made. Those of us who remember the days before widely available and easy-to-program microcontrollers will tell you that computer control of a small hardware project was certainly possible, but instead of dropping in a single chip it would have involved constructing an entire computer system. I remember Z80 systems on stripboard, with the Z80 itself alongside an EPROM, RAM chips, 74-series decoder logic, and peripheral chips such as the 6402 UART or the 8255 I/O port. Flashing an LED or keeping an eye on a microswitch or two became a major undertaking in both construction and cost, so we’d only go to those lengths if the application really demanded it. This changed for me in the early 1990s when the first affordable microcontrollers with on-board EEPROM came to market, but by then these chips had already been with us for a couple of decades.
It seems strange to modern ears, but for an engineer around 1970 a desktop calculator was a more exciting prospect than a desktop computer. Yet many of the first microcomputers were designed with calculators in mind, as was for example the Intel 4004. Calculator manufacturers each drove advances in processor silicon, and at Texas Instruments this led to the first all-in-one single-chip microcontrollers being developed in 1971 as pre-programmed CPUs designed to provide a calculator on a chip. It would take a few more years until 1974 before they produced the TMS1000, a single-chip microcontroller intended for general purpose use, and the first such part to go on sale. Continue reading “The TMS1000: The First Commercially Available Microcontroller”