paul@.Solbourne.COM (Paul Orland) (08/03/90)
>In article <9471> Eric Smith at goofy.Apple.COM writes: >In article <134023.285> paul@paul.Solbourne.COM >(Paul Orland)(Me) writes: >> >> As discussed in this forum previously, this is *not* true with disk >>drives. >> 1 Megabyte of disk space = 1,000,000 bytes (10^6), not 1024^2. > >As discussed in this forum previously, there is no consensus as to >whether a magabyte of disk space is 1000^2 or 1024^2 bytes, but for >consistency with RAM most people seem to use 1024^2. If you talk about >1K of disk space, you probably mean 1024 bytes, since 1024 probably has >a simple ratio to your sector size, whereas 1000 probably doesn't. If >you start from that reasoning, a megabyte of disk space is either >1024*1024 or 1024*1000. The latter doesn't seem to make much sense. --- I should of known better than to post information to this forum without backing it up. How 'bout some facts. The numbers in the following examples are taken directly from manufacturers specifications or calculated directly from numbers given. Example 1: Maxtor XT-4380S Disk Drive Unformatted Capacity/Drive = 384.46 "Mbytes" Unformatted Capacity/Track = 20,940 Bytes Tracks/drive = 18,360 18360 * 20940 = 384458400 If a "Mbyte" = 1024*1024, Drive Capacity = 366.65 <> 384.46 If a "Mbyte" = 1024*1000, Drive Capacity = 375.45 <> 384.46 If a "Mbyte" = 1000*1000, Drive Capacity = 384.46 = 384.46 So, a Maxtor unformatted "Mbyte" is = 1000*1000 or 10^6. Example 2: Hitachi DK514C-38 Disk Drive Formatted Capacity/Drive = 321.8 "MBytes" Formatted Capacity/Track = 25,600 Bytes User Tracks/drive = 898*14=12572 12572 * 256000 = 321843200 If a "MByte" = 1024*1024, Drive Capacity = 306.93 <> 321.8 If a "MByte" = 1024*1000, Drive Capacity = 314.30 <> 321.8 If a "MByte" = 1000*1000, Drive Capacity = 321.84 = 321.8 So, a Hitachi formatted "MByte" is = 1000*1000 or 10^6. Every drive specification I have seen follows these conventions. Have you seen any that don't? So don't you go trying to copy your 100 Mbytes of ram onto a 100 Mbyte disk anytime soon :-). -- ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ Paul Orland <> I/O Substystems <> Solbourne Computer paul@Solbourne.COM ---------- ...!{boulder,sun}!stan!paul
wschmidt%decefix@decefix.iao.fhg.de (Wolfram Schmidt) (08/03/90)
Quantum defines MB as 1,000,000 Bytes wschmidt@iao.fhg.de
josef@nixpbe.UUCP (Moellers) (08/09/90)
>In article <9471> Eric Smith at goofy.Apple.COM writes: >In article <134023.285> paul@paul.Solbourne.COM >(Paul Orland)(Me) writes: >> >> As discussed in this forum previously, this is *not* true with disk >>drives. >> 1 Megabyte of disk space = 1,000,000 bytes (10^6), not 1024^2. > >As discussed in this forum previously, there is no consensus as to >whether a magabyte of disk space is 1000^2 or 1024^2 bytes, but for >consistency with RAM most people seem to use 1024^2. If you talk about >1K of disk space, you probably mean 1024 bytes, since 1024 probably has >a simple ratio to your sector size, whereas 1000 probably doesn't. If >you start from that reasoning, a megabyte of disk space is either >1024*1024 or 1024*1000. The latter doesn't seem to make much sense. Well, compare the figures: A disk drive with a capacity of 162529280 bytes is either - 162.5 MBytes (where 1MB = 10^6 Bytes) or - 155 MBytes (where 1MB = 1024^2 Bytes). Now, if You read "Our disk drive has 162.5 MB capacity", doesn't that sound better that "Our disk drive has 155 MB capacity"? There's definitely a 7.5 MBytes difference in these figures! -- | Josef Moellers | c/o Nixdorf Computer AG | | USA: mollers.pad@nixbur.uucp | Abt. PXD-S14 | | !USA: mollers.pad@nixpbe.uucp | Heinz-Nixdorf-Ring | | Phone: (+49) 5251 104662 | D-4790 Paderborn |