It’s computers all the way down. We know about recursion in software, but it’s surprising to find it occurring in hardware. How many computers are really inside your computer? One? A couple? Maybe a dozen? In reality, it’s probably hundreds.
Normal people count the average PC, Mac, or Linux box as one computer. But, as engineers, we know there’s really more than one processor inside. But how many, really? In the early days of the IBM Personal Computer Model 5150, the keyboard had its own 8048 microcontroller chip that translated the up/down key actions into the weird IBM “scancodes” that PCs have used ever since. So that’s two processors…
Today, your PC’s video output is probably handled by a GPU from Intel, AMD, or nVidia. That’s one more processor — and a pretty elaborate one, too. GPUs are not simple machines, and they’re completely programmable, which makes them processors by any definition.
Depending on your GPU, it may have tens, hundreds, or even thousands of separate processing cores. Do we count each one separately, or treat them all as one GPU? Same goes for your computer’s main processor. It’s probably got four, eight, or more CPU cores.
Importantly, each one of those CPU cores is a complete processor that’s programmable and largely independent of its sibling CPU cores on the same die. Each core might also be dual- or multithreaded, nearly doubling its capabilities. Plus, there are security processors buried within the x86 processor, like the Intel Management Engine or AMD’s Platform Security Processor. Even the MMU can operate on its own. How many processors are we up to now?
Hard disk drives, SSDs, and optical drives all have their own controller ICs that contain one or more processors (probably ARM-based), and many of those are multi-core designs as well. Ethernet and Wi-Fi interfaces are processor-controlled, as are USB ports. Even USB cables have processors inside. Pluggable SD cards have their own internal controllers, not just memory. Got a fancy gaming rig with addressable LEDs, PWM fans, an AIO cooler, a Corsair controller, and DIMMs that light up? Guess what’s controlling all of those.
Then there are the…