3 ms·

Where does mebibyte come into play?

deleted 6y ago
[deleted]
Phrodo_00 6y ago
Mebibyte comes from pedants (like myself) that say that the Mega prefix in SI means 10^6, but in computing we often take it to mean 2^20. Mebibyte is unambiguous, and if everybody used it (unlikely. I don't think either MacOs or Windows use it), then Mega would also be. Right now, when you see mega in a computing context you're not sure if it means 10^6 or 2^20, although a lot of times it doesn't even matter.
- dr_zoidberg 6y ago
  Okay, this is second hand as I don't own a mac, but a friend who does noticed that on his macbook, macOS reports file sizes with megabyte being 10^6 bytes, whereas windows follos the 2^20 convention. He was going crazy over a file being shown as 600Mb on Windows and 629Mb on mac. When he compared the bytes values, they were the same (around 629,145,600 bytes) and that settled it.
  - stephenr 6y ago
    This is true, macOS reports it using decimal sizing. I believe the reason is that all storage devices are marketed in decimal sizes anyway.
  - rgovostes 6y ago
    They changed the behavior of macOS a number of years ago (2012?) because disk manufacturers advertise storage capacity in 10^x, and the operating system displaying sizes in 2^y made the disks seem smaller and (in theory) caused confusion. My MacBook Pro's internal "1 TB" disk is actually 1,000,240,963,584 bytes -- neither 1 TB nor 1 TiB.
    - jzer0cool 6y ago
      I remember this. The packaging showing the calculation that 1MB = 1024 bytes
  - saagarjha 6y ago
    Possibly interesting: https://developer.apple.com/documentation/foundation/bytecountformatter/countstyle https://developer.apple.com/documentation/foundation/bytecou...
  - seppel 6y ago
    > He was going crazy over a file being shown as 600Mb on Windows and 629Mb on mac. When he compared the bytes values, they were the same (around 629,145,600 bytes) and that settled it. To be fair: It make sense to measure RAM in MiB, because it is addressed by binary address lines so you always end up with a power of two. Files are, however, as big as somebody decided to write into them (modulo some rounding to the next sector, depending on file system implementation details). It does not make much sense to measure them in MiB. Quite often it just more confusing to calculate file sizes in MiB instead of MB. I dont even know why Microsoft stated that MiB business. Similar with hard disks by the way. They contain as many sectors as the manufacturer was able to put on them. There is no power of two involved.
- stephenr 6y ago
  It wouldn’t make sense for macOS to use the binary prefixes for file sizes, as it uses the decimal sizing method to show file sizes.
shawnz 6y ago
"Mebibyte" and similar units were only coined in 1998, a few years after the era of 4mb/8mb graphics cards.

deleted 6y ago

[deleted]

Mebibyte comes from pedants (like myself) that say that the Mega prefix in SI means 10^6, but in computing we often take it to mean 2^20. Mebibyte is unambiguous, and if everybody used it (unlikely. I don't think either MacOs or Windows use it), then Mega would also be. Right now, when you see mega in a computing context you're not sure if it means 10^6 or 2^20, although a lot of times it doesn't even matter.

dr_zoidberg 6y ago
Okay, this is second hand as I don't own a mac, but a friend who does noticed that on his macbook, macOS reports file sizes with megabyte being 10^6 bytes, whereas windows follos the 2^20 convention. He was going crazy over a file being shown as 600Mb on Windows and 629Mb on mac. When he compared the bytes values, they were the same (around 629,145,600 bytes) and that settled it.
- stephenr 6y ago
  This is true, macOS reports it using decimal sizing. I believe the reason is that all storage devices are marketed in decimal sizes anyway.
- rgovostes 6y ago
  They changed the behavior of macOS a number of years ago (2012?) because disk manufacturers advertise storage capacity in 10^x, and the operating system displaying sizes in 2^y made the disks seem smaller and (in theory) caused confusion. My MacBook Pro's internal "1 TB" disk is actually 1,000,240,963,584 bytes -- neither 1 TB nor 1 TiB.
  - jzer0cool 6y ago
    I remember this. The packaging showing the calculation that 1MB = 1024 bytes
- saagarjha 6y ago
  Possibly interesting: https://developer.apple.com/documentation/foundation/bytecountformatter/countstyle https://developer.apple.com/documentation/foundation/bytecou...
- seppel 6y ago
  > He was going crazy over a file being shown as 600Mb on Windows and 629Mb on mac. When he compared the bytes values, they were the same (around 629,145,600 bytes) and that settled it. To be fair: It make sense to measure RAM in MiB, because it is addressed by binary address lines so you always end up with a power of two. Files are, however, as big as somebody decided to write into them (modulo some rounding to the next sector, depending on file system implementation details). It does not make much sense to measure them in MiB. Quite often it just more confusing to calculate file sizes in MiB instead of MB. I dont even know why Microsoft stated that MiB business. Similar with hard disks by the way. They contain as many sectors as the manufacturer was able to put on them. There is no power of two involved.
stephenr 6y ago
It wouldn’t make sense for macOS to use the binary prefixes for file sizes, as it uses the decimal sizing method to show file sizes.

shawnz 6y ago

"Mebibyte" and similar units were only coined in 1998, a few years after the era of 4mb/8mb graphics cards.