system
Given the following post, respond as if you're commenting on Reddit:
human
Why have the number of "bits" in commercial computer processors stopped increasing?

In the 20th century, major advances in computing were marked by the number of bits the machine was capable of processing. 8 bit machines, 16 bit, 32 bit and then 64 bit. But it seems we never got to a 128 bit machine (or if we did it was never made commercially) why have commercial computers never adopted 128 bit technology?
gpt
TL;DR: We don’t need more. 64-bit computers will be around for a long time.

Some background.

Let’s take a very simple processor. It has 2 bits. This means it holds up to 4 possible values (00 = 0, 01 = 1, 10 = 2, and 11 = 3).

It can handle 2 bits of data at a time. It can receive 2 binary digits at a time, add 2-binary-digit numbers at a time, store 2-binary-digit numbers at a time, etc... Another thing it does 2-digit a time is address memory. Memory has different “slots”. Each slot has an address. So one instruction might be “store the current value in address 01”.

Knowing that, you now know the two major benefits of more bits: handling bigger numbers at the same time and being able to address bigger memory.

Let’s start with the memory. With 32 bits, you get 4 gigabytes of memory. Your processor can only use 4 gigabytes of memory because that’s all it can address. It doesn’t have enough bits to represent 4 gigabytes and 1. It’s like trying to represent the number 1000 with only 3 decimal places. You can only go up to 999.

We got to the point where we needed more than 4 gigabytes of memory so we created 64-bit computers. Because of the exponential nature of adding more digits where adding a digit doubles the number of values you can have, 64 bits give us a memory limit of 16 exabytes. That’s over 17,000,000 terabytes and we’re nowhere near 1 terabyte of memory.

The size of numbers it can handle at a time is even less impactful because:

1. It’s rare to need to use huge numbers like that in most applications.

2. It’s relatively easy to work around in applications that do need them.