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We'd be better off with 9-bit bytes

pavpanchekha.com

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Re: We'd be better off with 9-bit bytes

#101

Post by foxglacier »

marcosdumay wrote: post #50
zamadatix wrote: post #4

Because we have 8 bit bytes we are familiar with the famous or obvious cases multiples-of-8-bits ran out, and those cases sound a lot better with 12.5% extra bits. What's harder to see in this kind of thought experiment is what the famously obvious cases multiples-of-9-bits ran out would have been. The article starts to think about some of these towards the end, but it's hard as it's not immediately obvious how many…

Well, there should be half as many cases of multiples-of-9-bits ran out than for multiples-of-8-bits. I don't think this is enough of a reason, though.

If you're deciding between using 8 bits or 16 bits, you might pick 16 because 8 is too small. But making the same decision between 9 and 18 bits could lead to picking 9 because it's good enough at the time. So no I don't think there would be half as many cases. They'd be different cases.

Re: We'd be better off with 9-bit bytes

#103

Post by tzs »

pdpi wrote: post #18
Keyframe wrote: post #3

Yeah, but hear me out - 10-bit bytes!

One of the nice features of 8 bit bytes is being able to break them into two hex nibbles. 9 bits breaks that, though you could do three octal digits instead I suppose. 10 bit bytes would give us 5-bit nibbles. That would be 0-9a-v digits, which seems a bit extreme.

10-bit has sort of been used. The General Instrument CP1600 family of microprocessors used 16-bit words but all of the instruction opcodes only used 10 bits, with the remaining 6 bits reserved for future use.

GI made 10-bit ROMs so that you wouldn't waste 37.5% of your ROM space storing those 6 reserved bits for every opcode. Storing your instructions in 10-bit ROM instead of 16-bit ROM meant that if you needed to store 16-bit data in your ROM you would have to store it in two parts. They had a special instruction that would handle that.

The Mattel Intellivision used a CP1610 and used the 10-bit ROM.

The term Intellivision programmers used for a 10-bit quantity was "decle". Half a decle was a "nickel".

Re: We'd be better off with 9-bit bytes

#104

Post by adrianmonk »

> IPv4 would have had 36-bit addresses, about 64 billion total. That would still be enough right now, and even with continuing growth in India and Africa it would probably be enough for about a decade more. [ ... ] When exhaustion does set in, it would plausibly at a time where there's not a lot of growth left in penetration, population, or devices, and mild market mechanisms instead of NATs would be the solution.

I think it's actually better to run out of IPv4 addresses before the world is covered!

The later-adopting countries that can't get IPv4 addresses will just start with IPv6 from the beginning. This gives IPv6 more momentum. In big, expensive transitions, momentum is incredibly helpful because it eliminates that "is this transition even really happening?" collective self-doubt feeling. Individual members of the herd feel like the herd as a whole is moving, so they ought to move too.

It also means that funds available for initial deployment get spent on IPv6 infrastructure, not IPv4. If you try to transition after deployment, you've got a system that mostly works already and you need to cough up more money to change it. That's a hard sell in a lot of cases.

Re: We'd be better off with 9-bit bytes

#105

Post by mouse_ »

duskwuff wrote: post #17

Non-power-of-2 sizes are awkward from a hardware perspective. A lot of designs for e.g. optimized multipliers depend on the operands being divisible into halves; that doesn't work with units of 9 bits. It's also nice to be able to describe a bit position using a fixed number of bits (e.g. 0-7 in 3 bits, 0-31 in 5 bits, 0-63 in 6 bits), e.g. to represent a number of bitwise shift operations, or to select a bit from a…

Times have changed. Gnome people will yell at you for mentioning things as innocuous as pixel measurements. You'd probably be crucified for suggesting there's a hardware-correct way of handling address space.

Re: We'd be better off with 9-bit bytes

#106

Post by jacquesm »

PaulHoule wrote: post #56

I thought the PDP 10 had 6-bit bytes, or at least 6-bit characters https://en.wikipedia.org/wiki/Six-bit_character_code#DEC_SIX... Notably the PDP 8 had 12 bit words (2x6) and the PDP 10 had 36 bit words (6x6) Notably the PDP 10 had addressing modes where it could address a run of bits inside a word so it was adaptable to working with data from other systems. I've got some notes on a fantasy computer that has 48-bit…

You are correct. The Sperry-Univac 1100 series though did have 36 bit words and 9 bit bytes.

Re: We'd be better off with 9-bit bytes

#107

Post by elcritch »

adrianmonk wrote: post #104

> IPv4 would have had 36-bit addresses, about 64 billion total. That would still be enough right now, and even with continuing growth in India and Africa it would probably be enough for about a decade more. [ ... ] When exhaustion does set in, it would plausibly at a time where there's not a lot of growth left in penetration, population, or devices, and mild market mechanisms instead of NATs would be the solution. I…

And nothing like FOMO of developing markets not being able to access a product to drive VPs and CEOs to care about ensuring IPv6 support works with their products.

Re: We'd be better off with 9-bit bytes

#108

Post by jacquesm »

tzs wrote: post #103
pdpi wrote: post #18

Earlier quoted context omitted.

One of the nice features of 8 bit bytes is being able to break them into two hex nibbles. 9 bits breaks that, though you could do three octal digits instead I suppose. 10 bit bytes would give us 5-bit nibbles. That would be 0-9a-v digits, which seems a bit extreme.

10-bit has sort of been used. The General Instrument CP1600 family of microprocessors used 16-bit words but all of the instruction opcodes only used 10 bits, with the remaining 6 bits reserved for future use. GI made 10-bit ROMs so that you wouldn't waste 37.5% of your ROM space storing those 6 reserved bits for every opcode. Storing your instructions in 10-bit ROM instead of 16-bit ROM meant that if you needed to st…

That's a very interesting bit of lore, I knew those were peculiar CPUs but I never know about these details, thank you!

Re: We'd be better off with 9-bit bytes

#109

Post by gxs »

willis936 wrote: post #98
duskwuff wrote: post #17

Non-power-of-2 sizes are awkward from a hardware perspective. A lot of designs for e.g. optimized multipliers depend on the operands being divisible into halves; that doesn't work with units of 9 bits. It's also nice to be able to describe a bit position using a fixed number of bits (e.g. 0-7 in 3 bits, 0-31 in 5 bits, 0-63 in 6 bits), e.g. to represent a number of bitwise shift operations, or to select a bit from a…

Plato argued that 7! was the ideal number of citizens in a city because it was a highly factorable number. Being able to cut numbers up is an time-tested favorite. That's why there are 360 degrees.

Or 60 minutes in an hour

1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, and 60

Re: We'd be better off with 9-bit bytes

#110

Post by jacquesm »

labrador wrote: post #71
svachalek wrote: post #66

Earlier quoted context omitted.

As soon as that's my baseline assumption, I think I'm done with the internet. I can get LLM slop on my own.

I thought the article was well written. I'm assuming the author did most of the writing because it didn't sound like AI slop. I also assume he meant he uses AI to assist, not as the main driver.

It really wasn't well written. I contains factual errors that stand out like lighthouses showing the author had an idea about an article but doesn't actually know the material.
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