Zoë Blade's notebook


The microprocessor is perhaps the most significant invention of the 1970s. It's a small device that can perform logic and basic arithmetic. This allows it to execute computer programs.

A computer program itself is nothing more than a series of instructions that the processor can perform very quickly. The instructions generally involve copying numbers from one part of memory to another; performing division, multiplication, addition, and subtraction on them; repeating a set of tasks many times; and conditionally branching off to one set of instructions or another, based on whether a particular number is above or below a certain threshold.

At its core, that's really pretty much anything a microprocessor can do. It can seem like it does far more, but only because people have translated things like alphabets, colours, and sounds into numbers and back again. A microprocessor is the main component in a general-purpose computer, where it can be given arbitrary code to execute. It can also be found hidden away in a specific device like a traffic light, cash dispenser, or toy, executing one specialised, purpose-built computer program etched in ROM.


Microprocessors revolutionised almost every industry, including music.

They enabled step sequencers to evolve from simple analogue devices to digitally controlled ones, and to eventually even become MIDI sequencers; allowed polyphony by routing one set of controls to multiple voice boards; gave synthesisers memories in which to store programs; controlled oscillators to maintain perfect tuning; and ultimately, replaced a plethora of cables, each with their own protocol, with the unified MIDI standard.

They replaced recording playback keyboards — fringe novelty instruments like the Mellotron and Orchestron, which could musically play back recordings of other instruments playing single notes — with fully fledged samplers like the Fairlight CMI. They allowed John Chowning and Yamaha to take FM synthesis from something slowly computed by digital mainframes, and more primitively performed on analogue synthesisers, to a new series of light, portable, polyphonic keyboards that ushered in a new world of sounds.

Pretty much anything extolled as digital is thanks to microprocessors.

The general trajectory with microprocessors is they make everything else easier to use, before replacing those things entirely. Synthesisers were no exception. Once general-purpose computers had sound cards and enough processing power to turn audio into numbers, perform the complex maths required to emulate synthesisers, and turn those numbers back into audio again, there was no stopping them. MIDI sequencer software consumed the functionality of multitrack recorders and mixing desks, becoming DAWs. Then it consumed the functionality of synthesisers, samplers, and effects processors, gaining plug-ins. Now you can fit a whole studio inside a laptop. But for now, at least, analogue synthesisers with knobs and sliders can sound gloriously messier than their digital emulations, and are much less fiddly to wire up.

Example implementations

Microprocessors: 68000 | HD6303X | μPD780 | μPD8080 | μPD70216