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blog:pushbx:2026:0201_overview_of_educational_topics [2026-02-01 17:41:16 +0100 Feb Sun] ecm created |
blog:pushbx:2026:0201_overview_of_educational_topics [2026-02-01 17:49:37 +0100 Feb Sun] (current) ecm [Units and unit prefixes] fix expansion of MB unit |
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| Briefly, for SI the prefixes are powers of 10 (and the k short form for kilo is not capitalised). Therefore 1 kB for SI is 1000 Bytes, 1 MB is 1_000_000 Bytes, and so on. IEC uses kilo-binary or kibi, short Ki, for 1024, a power of 2. JEDEC abuses kilo (short as capital K) to mean 1024, hence 1 KB for 1024 Bytes. | Briefly, for SI the prefixes are powers of 10 (and the k short form for kilo is not capitalised). Therefore 1 kB for SI is 1000 Bytes, 1 MB is 1_000_000 Bytes, and so on. IEC uses kilo-binary or kibi, short Ki, for 1024, a power of 2. JEDEC abuses kilo (short as capital K) to mean 1024, hence 1 KB for 1024 Bytes. | ||
| - | One problem with the JEDEC use is that it becomes inconsistent when calculations involve different units. 1 MB is 1_048_576, but 1 MHz is 1_000_000 Hz. How much data does a transfer move that runs at 1 MHz and processes 1 Byte per cycle? Not "1 MB per second" | + | One problem with the JEDEC use is that it becomes inconsistent when calculations involve different units. 1 MB is 1_048_576 |
| The default format of the venerable 90mm diskette (aka "3½ inch" diskette) is not 1.44 of anything, neither MB (SI) nor MiB (IEC). It is actually 1440 KiB, which comes out to 1.47 MB or 1.40 MiB. | The default format of the venerable 90mm diskette (aka "3½ inch" diskette) is not 1.44 of anything, neither MB (SI) nor MiB (IEC). It is actually 1440 KiB, which comes out to 1.47 MB or 1.40 MiB. | ||