2001-06-16 Han, Please forward: 1.) But, my monitor as measure diagonally (corner to corner) is 400 mm. But, 17 inches is 432 mm, what happened to the lost 32 mm? Shouldn't my monitor be called a 15.7480315 inch (or more PRECISELY a 400 mm) monitor if the viewable diagonal dimension is only that? 2.) In the early 1990's JEDEC, which standardises the design of microchips, decided that pin spacing, on all new designs from that date forward must be in rational millimetres. The dimension can only be to two decimal places, in which the hundreds digit can only be a zero (0) or a (5). This rule does not affect old technology. Spacing were originally 0.1 in (2.54 mm) and halved to 0.05 in (1.27 mm) and would again have been halved to 0.025 in (0.635 mm). But, this last standard never came into existence. In order to conform to JEDEC rules, it had to be either 0.65 mm or 0.6 mm. 0.65 mm is what was chosen and that is the standard. Now, the newest standard is 0.5 mm. You can call them what you want in inches, but the rest of us will call them 0.65 mm and 0.5 mm. Even the inch spacing on terminal connectors is being phased out for hard metric. 2 mm and 1 mm connectors are the norm. Some terminal connectors were made in both 5.08 and 5 mm spacing, but the 5.08 is now obsolete. 3.) Funny thing you mention tape. I haven't bought tapes in years. I buy all my music on CD's and CD's are SI. Their diameter is 120 mm. That is the standard. There is also a smaller version that is 80 mm. Yes, old technology from the US is in old units, but new technology from Asia and Europe is metric. When you consider that the newest technology is coming out of Asia and Europe, yes, not being metric is holding the US back. Give me some present day examples, not decade old. Han, They didn't answer the questions asked. Can you prod them! They completely avoided the important issues. John Keiner ist hoffnungsloser versklavt als derjenige, der irrt�mlich glaubt frei zu sein. There are none more hopelessly enslaved then those who falsely believe they are free! Johann Wolfgang von Goethe (1749-1832) ----- Original Message ----- From: "Han Maenen" <[EMAIL PROTECTED]> To: "U.S. Metric Association" <[EMAIL PROTECTED]> Sent: Saturday, 2001-06-16 13:34 Subject: [USMA:13808] Fw: Questions about measurement standards > One answer from the BWMA. > > Han > > ----- Original Message ----- > From: "Joseph B. Fox" <[EMAIL PROTECTED]> > To: "Han Maenen (by way of mail <[EMAIL PROTECTED]>)" > <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>; > [EMAIL PROTECTED]>; <[EMAIL PROTECTED]>; > <[EMAIL PROTECTED]; [EMAIL PROTECTED]>; > [EMAIL PROTECTED]>; <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> > Sent: Saturday, June 16, 2001 5:45 PM > Subject: Re: Questions about measurement standards > > > > TV screens and computer monitors are sized according to the dimension of > their diagonals. A 17" screen, for example, measures seventeen inches from > corner to corner. There are two good reasons for this. Firstly, the > original cathode ray tubes were round - the rectangular image was projected > onto them, with the corners just touching the outside of the circle. So the > "diagonal" measure was also the diameter of the tube. Secondly, until the > advent of widescreen TV, all the images were in the 3:4 format. Remember > your Pythagorus: the diagonal of a 3:4 rectangle is... 5. So divide the > diagonal measure of your screen by five and multiply by three for height and > by four for width. > > > > But why inches? Because the technology was developed in non-metric > America. ISO notwithstanding, computer components tend to be designed in > imperial increments. The ISO may say that the connectors on a processor > should be > 2.54mm apart: we know that that really means one tenth of an inch. > > > > Similarly, you will find that with few exceptions, all the standards > pertaining to magnetic recording tape are (were) imperial: quarter inch > tape, fifteen inches per second, etc. Same reason - made in America. God, > how refusing to adopt the metric system has held them back! > ---------- > From: "Han Maenen" <[EMAIL PROTECTED]> (by way of mail > <[EMAIL PROTECTED]>) > To: [EMAIL PROTECTED], [EMAIL PROTECTED], > [EMAIL PROTECTED], [EMAIL PROTECTED], > [EMAIL PROTECTED], [EMAIL PROTECTED], [EMAIL PROTECTED], > [EMAIL PROTECTED], [EMAIL PROTECTED] > Subject: Questions about measurement standards > Date: Jun 16, 2001, 07:41 > > Any replies? ss > > > Dear Mr Delaney, > > I have some questions about standards. Could the BWMA answer these for me? > > 1.) The BWMA claims the floppy disk is imperial because it is called 3.5 > inch. Which dimension does the 3.5 inch refers to? Is the BWMA aware of the > ISO 9529-1 specification for floppy disks? This specification require the > floppy disk to be 94 mm x 90 mm x 3.3 mm. The disk to be 86 mm in diameter > and the mass to be 24 g. > > Why does BWMA's material state that a conversion of 3.5 inch would result in > either an 88.9 mm name or an 89 mm name? Since the spec calls for one of > the dimensions to be 90 mm, why not call it by this name? At least the name > would match and actual dimensional part of the device. > > 2.) Why do computer monitors use inches for one dimension but don't follow > through and use millimetres for dot pitch? Also, the manual for the > Optiquest V73 calls it a 17 inch monitor, but gives the maximum viewing area > as 325 mm x 244 mm and the default as 300 x 225 mm. It contains no > information at all about what the 17 inch is supposed to refer to. > The physical dimensions of the whole monitor are 405 mm x 405 mm x 425 mm, > or 15.9" x 15.9" x 16.7". Is it a common practice to use inch numbers that > don't refer to any part of the product? What is the purpose? > > 3.) How does the BWMA define the foot, inch, pound, the Imperial gallon > etc.? Does the organization u accept the present "official" definition of > the units as 0.3048 m, 0.0254 m, 0.4536... kg, etc.? If the BWMA doesn't > accept the "official" definitions, how does it account for any errors that > will exist between their definitions and the "official" versions? > > Yours faithfully, > > Han Maenen > > [EMAIL PROTECTED] > >
