5 ms·

I did not know that was ever a thing. I knew that bit counts had been lower - 5 or 6 - but assumed once we hit 8, the whole power-of-2 thing was too comfortable

I did not know that was ever a thing. I knew that bit counts had been lower - 5 or 6 - but assumed once we hit 8, the whole power-of-2 thing was too comfortable in a binary system to ever be anything besides a power of 2 again - and sure enough, we get 16 bit, 32 bit, and 64 bit systems, and double-byte and triple-byte char sets, etc. Need more space? Take another byte. Was the 9th bit special? Or just a standard bit in the byte?

Lx1oG-AWb6h_ZG0 11y ago
Someone probably read too much Iain M. Banks and decided to adopt Marain's base-9 system :) If I'm not mistaken, some old consoles used a 9-bit RGB encoding, so this could theoretically help there. Minecraft also uses a 9-bit system for Redstone, afaik.
chiph 11y ago
The PowerPC based AS/400 systems were technically 65-bit machines, as the extra bit was a privilege flag to separate system code from user code. Hardware enforced security - one reason why it is such a stable machine.
Someone 11y ago
36 bit was popular for scientific computing because 35 gives you a sign bit and 10 decimal digits (yes, that's weird, but that's the argument I read everywhere, including at https://en.m.wikipedia.org/wiki/36-bit https://en.m.wikipedia.org/wiki/36-bit. 35 likely was skipped because it its only divisors are 5 and 7, limiting instructions to 7 bits even then was felt to be too restricting. For some architectures, the DoD had a say in this, too. See https://en.m.wikipedia.org/wiki/Unisys_2200_Series_system_architecture https://en.m.wikipedia.org/wiki/Unisys_2200_Series_system_ar...) 36 bits got us the 6-bit character (10 digits, 26 letters, and punctuation) with six characters in a word. Because of that, some OSes had six-character file names. If you want to get upper- and lowercase, you need more than 6 bits. 9 is the smallest divisor larger than 6 of 36, so nine-bit characters made sense. On such systems, file names could still use 6-bit characters, while applications used 9-bit ones. Also, some instructions could work on words, half words, quarter words, or sixth words.
wmf 11y ago
If hex hadn't been invented yet, 9 bits works better with octal. I don't know if that was a factor.

Lx1oG-AWb6h_ZG0 11y ago

Someone probably read too much Iain M. Banks and decided to adopt Marain's base-9 system :) If I'm not mistaken, some old consoles used a 9-bit RGB encoding, so this could theoretically help there. Minecraft also uses a 9-bit system for Redstone, afaik.

chiph 11y ago

The PowerPC based AS/400 systems were technically 65-bit machines, as the extra bit was a privilege flag to separate system code from user code. Hardware enforced security - one reason why it is such a stable machine.

Someone 11y ago

36 bit was popular for scientific computing because 35 gives you a sign bit and 10 decimal digits (yes, that's weird, but that's the argument I read everywhere, including at https://en.m.wikipedia.org/wiki/36-bit https://en.m.wikipedia.org/wiki/36-bit. 35 likely was skipped because it its only divisors are 5 and 7, limiting instructions to 7 bits even then was felt to be too restricting. For some architectures, the DoD had a say in this, too. See https://en.m.wikipedia.org/wiki/Unisys_2200_Series_system_architecture https://en.m.wikipedia.org/wiki/Unisys_2200_Series_system_ar...) 36 bits got us the 6-bit character (10 digits, 26 letters, and punctuation) with six characters in a word. Because of that, some OSes had six-character file names. If you want to get upper- and lowercase, you need more than 6 bits. 9 is the smallest divisor larger than 6 of 36, so nine-bit characters made sense. On such systems, file names could still use 6-bit characters, while applications used 9-bit ones. Also, some instructions could work on words, half words, quarter words, or sixth words.

wmf 11y ago

If hex hadn't been invented yet, 9 bits works better with octal. I don't know if that was a factor.