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> I can definitely imagine a counterfactual where 12bit bytes became the basic building block. It's definitely fun to imagine. I personally have a soft spot fo

> I can definitely imagine a counterfactual where 12bit bytes became the basic building block. It's definitely fun to imagine. I personally have a soft spot for a hypothetical ternary architectures, where the "trits" are either -1, 0 or 1. There's a mathematical elegance to that number system that binary can't match. > 12bit bytes also work great for encoding RGB values for video Can you elaborate, do you mean historically? The more bits the better, of course -- I get why 12 are better than 8, but it's not clear to me why you would want to stop at 12 bits. And if you don't stop there, what's the advantage? > The << and >> bitshift operators even on a 64bit number are only using 6 bits of their operand, so even on an 8-bit-centric architecture you’re not realizing any great synergy with the powers of two. 6 bits is still cleaner than the 6.58 bits required to encode shifts for this hypothetical 96-bit architecture, just use the lowest 6 address lines. And in general I think there are more places where stuff like this comes up than is apparent at first glance. How many bytes in a page? How many pages in a RAM chip? How many address lines and data lines? In the current era, RAM chips are agnostic about word size (as long as it's a power of two) because what they actually address are these much larger pages that chips can cut up in any way they want. Perhaps if everything standardized to 12 bits as the base at once, you could solve that or find workarounds, but I think would be mathematically tedious at every turn. It's so easy to just chop off a few bits and not worry about it.

jameshart 4y ago
To elaborate on “12bit bytes also work great for encoding RGB values for video”: I just mean that it’s easy to encode an RGB value as three four-bit values in a 12-bit number. Aligning ‘memory addresses’ to ‘pixels’ would simplify video hardware. Historically, 4096-color modes based on 12-bits-per-pixel were used (notably on the Amiga), in spite of byte-alignment issues. And of course 24-bit pixels would map to the common 16m colors we all know and love. 8, 16 and 32 bit architectures have always had compromises of one sort or another for storing three color channels - I half feel like the ubiquity of ARGB in modern graphics is down to our finally accepting that storage and memory are now cheap enough we should stop worrying about waste, pad out pixels with another channel, and just find a use for it. Transparency? Sure, why not. Regarding how RAM is laid out… a lot of early computers used ram chips striped by bit - so they’d have eight ram chips all wired to the same address bus, with each responsible for storing one data line for each address. Twelve bit memory is just laying four more data lines and adding four more chips. In my hypothetical counterfactual universe, obviously if 12 bit bytes win, later memory architectures are built around 12/24/48/96 bit data buses, so whatever paging and slicing they do would be within that model.
- codeflo 4y ago
  Interesting. Also, 8 bits per channel isn't even a natural endpoint. 256 values aren't enough to cover the full range of human perception to any reasonable accuracy, which is why 16-bit floating point per channel is now sometimes used to encode HDR. (But to be clear, at current RAM sizes, it wouldn't really matter what the base is.)
Dylan16807 4y ago
RAM chips already use weird numbers of bits all over. For example, DDR4 has 3 bits for chip select, 2 bits for bank group, 2 bits for bank, 18 bits for row, and 10 bits for column. This change wouldn't affect them in any meaningful way. And in the old days you had arbitrary numbers of address bits too, based on your chip size. I don't see any problems. Besides, RAM is generally a bunch of chips in parallel, so you could use our world's chips with no change. For example, put 6 on a stick instead of 8.

jameshart 4y ago

To elaborate on “12bit bytes also work great for encoding RGB values for video”: I just mean that it’s easy to encode an RGB value as three four-bit values in a 12-bit number. Aligning ‘memory addresses’ to ‘pixels’ would simplify video hardware. Historically, 4096-color modes based on 12-bits-per-pixel were used (notably on the Amiga), in spite of byte-alignment issues. And of course 24-bit pixels would map to the common 16m colors we all know and love. 8, 16 and 32 bit architectures have always had compromises of one sort or another for storing three color channels - I half feel like the ubiquity of ARGB in modern graphics is down to our finally accepting that storage and memory are now cheap enough we should stop worrying about waste, pad out pixels with another channel, and just find a use for it. Transparency? Sure, why not. Regarding how RAM is laid out… a lot of early computers used ram chips striped by bit - so they’d have eight ram chips all wired to the same address bus, with each responsible for storing one data line for each address. Twelve bit memory is just laying four more data lines and adding four more chips. In my hypothetical counterfactual universe, obviously if 12 bit bytes win, later memory architectures are built around 12/24/48/96 bit data buses, so whatever paging and slicing they do would be within that model.

codeflo 4y ago
Interesting. Also, 8 bits per channel isn't even a natural endpoint. 256 values aren't enough to cover the full range of human perception to any reasonable accuracy, which is why 16-bit floating point per channel is now sometimes used to encode HDR. (But to be clear, at current RAM sizes, it wouldn't really matter what the base is.)

Dylan16807 4y ago

RAM chips already use weird numbers of bits all over. For example, DDR4 has 3 bits for chip select, 2 bits for bank group, 2 bits for bank, 18 bits for row, and 10 bits for column. This change wouldn't affect them in any meaningful way. And in the old days you had arbitrary numbers of address bits too, based on your chip size. I don't see any problems. Besides, RAM is generally a bunch of chips in parallel, so you could use our world's chips with no change. For example, put 6 on a stick instead of 8.