On 06/30/2010 03:42 AM, R.S. wrote: > Ted MacNEIL pisze: >>> 2G = 2,000,000,000 >>> 2Gi = 2,147,483,648 >> >> Where is 2Gi a documented standard, other than IBM-Main? > Yes. This is official (documented standard) way of naming "binary > prefixes". However it's rarely used. > For example - IBM mainframe documentation widely use "the old way", that > mean no MiB, GiB, or KiB can be observed. > > >> This is as pedantic as the 'true meaning' of USS. > No. "Meaning of USS" is idee fixe of one or two guys on this forum. It > is NOT a standard. > USS is widely used as Unix System Services even by IBM. Sometimes > mentioned "IBM official acronym" is NOT documented for public - there > are no such "list of official IBM acronyms" available. > Last, but not least: acronym is a matter of English language, not an > asset of any company. And it's natural feature of acronym to be > overloaded (to have more than 1 meaning). > > >> To me, 2048M is 2G, and when it's on disk, 2000M is 2G. > And for most IT-specialists too, including IBM mainframe. > > >> That was the distinction taught in University in the 1970's. > This isn't good argument. Times are a changing. You probably were not > taught about EURO currency or 64-bit JAVA.
> Regards In the 1970's this distinction was actually explicitly documented in IBM Manuals for the S/360 family, that K & M were 2**10, 2**20 for memory but 10**3 and 10**6 for other contexts (DASD). Those in the profession understood it was the binary addressing of memory and non-binary constraints on DASD that made these distinctions rational. On architectures with decimal memory addressing, K was still 10**3, and on architectures with binary addressing but where machine words and instructions were written in octal, K = 2**9 was even used. Then came the great influx of newbies with the PC revolution in the late 1980's and 1990's and people unfamiliar with hardware architecture and the motivations behind the distinction began randomly using the "binary" prefixes in inappropriate contexts. The only way to eliminate the resulting mishmash and ambiguity was to come up with a new standard. Hopefully it won't take another 30 years for people to learn how to use it! -- Joel C. Ewing, Fort Smith, AR [email protected] ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
