Intel’s 8086 CPU turns 35, as fast as Arduino?

unoNo-one seemed to make much noise about it but Intel’s first x86 processor, the 8086, turned 35 on June 8. The chip spawned the X86 architecture that exists today.

Looking back at the specs, they’re not fancy reading by today’s standards, but they introduced the computer to business as a serious tool and it never looked back.

The 8086 was available in three clock speeds: 5MHz, 8MHz and 10MHz but it was the 8MHz variant that appeared in the original IBM XT computer. At that rate, it had processing speed of approximately 0.66MIPS. The chip itself was huge for the day, fitting inside a 40-pin DIP package but only housed 29,000 transistors. Those transistors were fabricated on a 3um (3000-nanometre) scale – today’s Intel Haswell chips have transistors that are more than 100 times smaller. The 8086 could also address a huge 1MB of memory.

So how does it compare with today’s hardware? You could argue for days over which CPU would come close to matching it equally today, but could the microcontroller behind the Arduino, Atmel’s ATMEGA328P, be a contender? At 16MHz, Atmel says the 328P has processing speed ‘approaching 1MIPS’ and according to one forum post, the Atmel MEGA core has approximately 20,000 gates or 80,000 transistors but by the time you add in SRAM and on-board flash, it comes closer to one million.

Clearly, there are obvious differences between the 8086 and ATMEGA328P, especially with the 328P limited to just 2KB of RAM. While the 8086 is generally seen as an 8-bit CPU, it did have some 16-bit capabilities thanks to a small handful of 16-bit registers within the CPU – AX, BX, CX, DX – that could also be split into 8-bit registers. The ATMEGA328P also has something approaching this with six of its 32 8-bit registers usable in a 16-bit mode, called the X-, Y-, and Z-registers, one notable use is the 328P’s built-in 16-bit timer.

The 8086 on the other hand, doesn’t have the ADCs (analog to digital converters) the ATMEGA328P has at its disposal but clearly, the 8086 and ATMEGA328P are designed for completely different applications. Still, it’s an interesting exercise to see how the founding chip of modern computing stacks up 35 years later. Clearly, we’ve come an awfully long way since then.

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