you know how Atari called the Jaguar as a "64bit system", because it had two 32bit CPUs? (or because it had a 64bit bus, but let's not worry about that)
we should apply that logic to the current generation of consoles.
So the Switch is a 256bit console. It's the Nintendo 256.

The Xbox Series X? terrible name.
Better call it the "Xbox 512 Blu-ray".
like the Jaguar CD, the Sega CD... the good old days when consoles had their media type in the name.

Boringly the PS5 is also a Playstation 512 Blu-ray, because both of them are using the same AMD Zen 2 CPU.

The Switch one is weeeird. It's built on an Nvidia Tegra X1, which is an 8 core 64-bit CPU, so that should be 512, right?

Well... no. Four of them can't be used. And later documentation doesn't even mention them.

it's some weird system where the system-on-a-chip has four Cortex-A57 cores and four Cortex-A53 cores but only the A57s are usable?

and it's not like "oh, games use the A57s and the A53s are used for low-powered things like the OS", because games actually only run on three of the A57s, with one reserved for the OS!
So you could instead argue the switch is a 192-bit system, by that logic.

the implication seems to be that Nvidia designed the system-on-chip to be 8-core, with 4 main cores and 4 secondary cores, as effectively two processors.
Then they discovered the secondary cores don't work properly, but shipped it anyway.

The later TM660M model of the chip just says it has 4 cores, the A57s... but it's possible the A53s are still on there too, just as dead silicon

I tried to look up the official Tegra X1 page and... huh.

NVIDIA DID YOU BREAK YOUR CPU SO BAD THAT ONLY HALF OF IT WORKS, THEN HOST YOUR WEBSITE ON IT?

anyway I did find one mention that the chip can't power both sets of cores at once.
so presumably this setup was originally designed for things like phones, where sometimes you want MAX PERFORMANCE but most of the time you just want power efficiency?

so even if it was functionally designed as 8 separate cores, it can only be used as the 4 performance cores or the 4 efficiency cores.

so it's like a turbo switch

(no nintendo pun intended.)

it's just a broken turbo switch that's stuck on

this is ARM's big.LITTLE system.
fun fact: some of the implementations of this technology are operating system transparent: the code running on it doesn't even need to know it's running on 8 cores instead of 4.

and the CPU can just transparently switch between running on the fast CPUs and the low CPUs, based on things like temperature and battery power. The OS doesn't need to know.

Then there's a version where the OS knows there's different cores (or at least that it can switch performance modes) and can toggle them as needed, per-core.
So you can have an 8 core system (4 fast 4 slow) and use any 4 of them at once, depending on demand.

then some CPUs have all cores functional at once, but the OS knows that some are faster than others, and therefore can intelligently assign threads to fast or slow cores as needed.
The Apple A-series chips, for example, work this way.

ARM has developed a successor to big.LITTLE, called DynamIQ.
big.LITTLE works on clusters, where each cluster is a grouping of identical cores. DynamIQ makes it so that clusters can be heterogenous core collections, as well as supporting more of them

so you can have 8 cores in a cluster and up to 32 clusters.
I can't wait for the Xbox Aleph null which deploys this configuration.
Eight 64bit ARM A57 clusters, 32 of them, for a 16384bit CPU

the die is 8 inches across, has a yield of 3 per fortnight, and requires active liquid helium cooling

BTW, if you accept the "external bus width = consoles bit width" thing to explain why the Atari Jaguar is 64bit despite having 32bit CPUs, it means the IBM PC/XT isn't a 16bit architecture despite using a 16bit processor.
It's an 8-bit system!

Because the IBM PC & IBM XT were built on the Intel 8088 version of the Intel 8086 chip. Both are 16-bit internally, but the 8088 uses an external 8-bit bus to make it cheaper to interface with.