Intel 8080 – the chip that changed the world

By Thomas Bartlett

Do you have a media centre? Of course you know that these are, at heart, Windows computers tuned towards multimedia performance. What you may not be as familiar with is that little bit of silicon deep in its heart.

Today it is likely to be some form of Pentium central processing unit. But it is a direct descendent of a device that hit the market in April 1974.

That product was the Intel 8080, a humble microprocessor.

Do you recall – assuming that you are old enough to have done so – using a computer powered by the Intel 8080? Probably not. The 8080 never became famous in the way that later computer processors did. But it deserves its place here because the processors that power the overwhelming majority of computers available today are derived from this chip.

Let us go back in time, briefly, to April 1974. There were what could be called ‘personal computers’ around. But they were large and extremely expensive. It was still a little over three years away from the release of the first ‘home computer’ – generally agreed to be the Apple II – which established the pattern for computers that has been followed ever since.

The Apple II did not use an Intel 8080 chip, but in fact a quite different processor from MOS Technology, called the 6502. Weeks after the appearance of the Apple II, Tandy released the first model of its computer: the TRS-80. This did not use an Intel 8080 either.

What the TRS-80 used was the Zilog Z80 chip. The Z80 and the 6502 were the dominant processors in home computers in the early days yet both, as far as general purposes computers went, eventually became dead ends.
Still, the Z80 was an important processor — and not only because my first two computers were based on it. The Zilog Z80 was designed by the same man who designed the 8080, and it was designed to use the same ‘instruction set’ as the 8080, and be compatible with it in all other ways. Just better.

The Intel 8080 was designed under the guidance of Intel employee Federico Faggin. At the end of 1974 Faggin left Intel to found Zilog. It was no wonder that the Z80 was compatible with the 8080. So useful was the Z80 that it remains in production today, for use as a low cost control processor for various machines.

Meanwhile, within Intel development continued. The core instructions used in the 8080 were retained, as were the ‘registers’ (the main working memories within the processor), and the 8085 chip was born. This could still run programs written for the 8080. More powerful though it may have been, it has largely been forgotten in the light of its famous offspring: the 8088.

This processor was still using basically the same instructions and registers as the 8080, but upgraded from 8- to 16-bit operation (allowing the easy manipulation of much larger numbers). What set the 8088 apart was that IBM selected it as the processor for its Personal Computer. With that, Intel was set on the path to becoming the giant that it now is.

The 8088’s function was replaced, later, with the 80286, the 80386, the 80408, the Pentium and all of its subsequent developments. The PC/Windows market rests on the offspring of the Intel 8080.

And so has, since 2006 when Apple switched over the Intel processors, the Apple Mac computer. So not only does your Media Center PC come from the 8080, so does the major potential competition.

Meanwhile, that other, lesser known, descendent of the 8080, the Zilog Z80, continues to quietly chug away providing the intelligence of a host of machines.