5 ms·

AFAIK network and HDDs were always measured in si units, only RAM was measured in powers of 2.

deleted 4y ago
[deleted]
microtonal 4y ago
For hard drives it was complicated, since their size is a function of the number of cylinders, heads, and sectors. Since the sector size is normally 512 bytes, they were a multiple of that. See e.g. this table of old hard drives: https://www.computerhope.com/hdquantu.htm https://www.computerhope.com/hdquantu.htm E.g., if you take the Quantum Bigfoot 1.2 GB model: 2492 cylinders * 16 heads * 63 sectors * 512 bytes per sector = 1286111232 bytes The size it was sold as, is definitely closer GiB (as in power of two): 1.2 * 2*30 = 1288490189 With rounding, they could sell it as 1.3 GiB with the current marketing trick of using SI units. So the old branding strategy seems to have been: compute the size in bytes, then find a reasonably MiB or GiB value (powers of two).
- kloch 4y ago
  The gap between SI prefixes and their base-2 approximations grows as sizes get larger. Before 1GB HDD’s the file system overhead was a much more dramatic effect so it didn’t really matter to consumers which prefix convention they used or how they rounded.
- CorrectHorseBat 4y ago
  As I see it the GB numbers are powers of 1000 rounded down: 2492 * 16 * 63 * 512 / 1000 ^ 3 = 1.286111232 4092 * 16 * 63 * 512 / 1000 ^ 3 = 2.111864832 4994 * 16 * 63 * 512 / 1000 ^ 3 = 2.577383424 Using GiB you get different numbers if you look past the first element in the table: 2492 * 16 * 63 * 512 / 1024 ^ 3 = 1.197784423828125 4092 * 16 * 63 * 512 / 1024 ^ 3 = 1.966827392578125 4994 * 16* 63 * 512 / 1024 ^ 3 = 2.4003753662109375 So I stand by my point, they have always used SI units. It's only ram (and software) that used incorrect definitions of k, M, G and T.
- mlyle 4y ago
  The whole power-of-10 thing for storage goes back forever-- to IBM mainframes and to the first hard drives used in PCs. E.g. Seagate ST-506, first 5.25" hard drive. "The total formatted capacity of the four heads and surfaces is 5/10 megabytes (32 sectors per track, 256 bytes per sector, 612/1224 tracks)." 612 * 32 * 256 = 5013504, or 5.01 megabytes or 4.78 mebibytes.

deleted 4y ago

[deleted]

For hard drives it was complicated, since their size is a function of the number of cylinders, heads, and sectors. Since the sector size is normally 512 bytes, they were a multiple of that. See e.g. this table of old hard drives: https://www.computerhope.com/hdquantu.htm https://www.computerhope.com/hdquantu.htm E.g., if you take the Quantum Bigfoot 1.2 GB model: 2492 cylinders * 16 heads * 63 sectors * 512 bytes per sector = 1286111232 bytes The size it was sold as, is definitely closer GiB (as in power of two): 1.2 * 2*30 = 1288490189 With rounding, they could sell it as 1.3 GiB with the current marketing trick of using SI units. So the old branding strategy seems to have been: compute the size in bytes, then find a reasonably MiB or GiB value (powers of two).

kloch 4y ago
The gap between SI prefixes and their base-2 approximations grows as sizes get larger. Before 1GB HDD’s the file system overhead was a much more dramatic effect so it didn’t really matter to consumers which prefix convention they used or how they rounded.
CorrectHorseBat 4y ago
As I see it the GB numbers are powers of 1000 rounded down: 2492 * 16 * 63 * 512 / 1000 ^ 3 = 1.286111232 4092 * 16 * 63 * 512 / 1000 ^ 3 = 2.111864832 4994 * 16 * 63 * 512 / 1000 ^ 3 = 2.577383424 Using GiB you get different numbers if you look past the first element in the table: 2492 * 16 * 63 * 512 / 1024 ^ 3 = 1.197784423828125 4092 * 16 * 63 * 512 / 1024 ^ 3 = 1.966827392578125 4994 * 16* 63 * 512 / 1024 ^ 3 = 2.4003753662109375 So I stand by my point, they have always used SI units. It's only ram (and software) that used incorrect definitions of k, M, G and T.
mlyle 4y ago
The whole power-of-10 thing for storage goes back forever-- to IBM mainframes and to the first hard drives used in PCs. E.g. Seagate ST-506, first 5.25" hard drive. "The total formatted capacity of the four heads and surfaces is 5/10 megabytes (32 sectors per track, 256 bytes per sector, 612/1224 tracks)." 612 * 32 * 256 = 5013504, or 5.01 megabytes or 4.78 mebibytes.