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SoftwareCPR provides these FDA related software and computer news items. Click Whats New at CDRH, Whats New at CDER, or Whats New at CBERto see new items listed on. Binary prefix Wikipedia. A binary prefix is a unit prefix for multiples of units in data processing, data transmission, and digital information, notably the bit and the byte, to indicate multiplication by a power of 2. The computer industry has historically used the units kilobyte, megabyte, and gigabyte, and the corresponding symbols KB, MB, and GB, in at least two slightly different measurement systems. In citations of main memory RAM capacity, gigabyte customarily means 7. As this is a power of 1. In most other contexts, the industry uses the multipliers kilo, mega, giga, etc., in a manner consistent with their meaning in the International System of Units SI, namely as powers of 1. For example, a 5. Gbits gigabit per second Ethernet connection transfers data at 7. In contrast with the binary prefix usage, this use is described as a decimal prefix, as 1. The use of the same unit prefixes with two different meanings has caused confusion. Starting around 1. International Electrotechnical Commission IEC and several other standards and trade organizations addressed the ambiguity by publishing standards and recommendations for a set of binary prefixes that refer exclusively to powers of 1. CONTROL VALVE HANDBOOK Third Edition FISHER CONTROLS INTERNATIONAL, INC Marshalltown, Iowa 50158 U. S. A. Cernay 68700 France Sao Paulo 05424 Brazil Singapore 128461. Accordingly, the US National Institute of Standards and Technology NIST requires that SI prefixes only be used in the decimal sense 1kilobyte and megabyte denote one thousand bytes and one million bytes respectively consistent with SI, while new terms such as kibibyte, mebibyte and gibibyte, having the symbols Ki. B, Mi. B, and Gi. B, denote 1. 02. 4 bytes, 7. In 2. 00. 8, the IEC prefixes were incorporated into the ISOIEC 8. HistoryeditMain memoryeditEarly computers used one of two addressing methods to access the system memory binary base 2 or decimal base 1. For example, the IBM 7. IBM 7. 02 1. 95. By the mid 1. Pc Move Software Comparison. Leathercraft Tools Uk on this page. This is the most natural configuration for memory, as all combinations of their address lines map to a valid address, allowing easy aggregation into a larger block of memory with contiguous addresses. Early computer system documentation would specify the memory size with an exact number such as 4. These are all powers of two, and furthermore are small multiples of 2. As storage capacities increased, several different methods were developed to abbreviate these quantities. Lantinghei Sc Font more. The method most commonly used today uses prefixes such as kilo, mega, giga, and corresponding symbols K, M, and G, which the computer industry originally adopted from the metric system. The prefixes kilo and mega, meaning 1. World War II. 4 Along with giga or G, meaning 7. SI prefixesdefn. International System of Units SI, introduced in 1. The International System of Units does not define units for digital information but notes that the SI prefixes may be applied outside the contexts where base units or derived units would be used. But as computer main memory in a binary addressed system is manufactured in sizes that were easily expressed as multiples of 1. This usage is not consistent with the SI. Compliance with the SI requires that the prefixes take their 1. The use of K in the binary sense as in a 3. K core meaning 3. Gene Amdahls seminal 1. IBM System3. 60 used 1. K to mean 1. 02. This style was used by other computer vendors, the CDC 7. System Description 1. K as 1. 02. 4. 9 Thus the first binary prefix was born. Another style was to truncate the last three digits and append K, essentially using K as a decimal prefixdefn. SI, but always truncating to the next lower whole number instead of rounding to the nearest. The exact values 7. K, 6. 5K and 1. K. If these values had been rounded to nearest they would have become 3. K, 6. 6K, and 1. 31. K, respectively. This style was used from about 1. These two styles K 1. In discussions of binary addressed memories, the exact size was evident from context. For memory sizes of 4. K and below, there is no difference between the two styles. The HP 2. MX real time computer 1. K and 7. 00. 61. M,1. HP 3. K, 9. 6K, or 1. K bytes of memory. The truncation method gradually waned. Capitalization of the letter K became the de facto standard for binary notation, although this could not be extended to higher powers, and use of the lowercase k did persist. Nevertheless, the practice of using the SI inspired kilo to indicate 1. For example, a 5. RAM module is 5. 121. The symbols Kbit, Kbyte, Mbit and Mbyte started to be used as binary unitsbit or byte with a multiplier that is a power of 1. For a time, memory capacities were often expressed in K, even when M could have been used The IBM System3. Model 1. 58 brochure 1. Real storage capacity is available in 5. K increments ranging from 5. K to 2,0. 48. K bytes. Megabyte was used to describe the 2. DEC PDP 1. 17. 0 1. DEC VAX 1. 17. 80 1. In 1. 99. 8, the International Electrotechnical Commission IEC introduced the binary prefixes kibi, mebi, gibi. The IEC prefixes were defined for use alongside the International System of Quantities ISQ in 2. Disk driveseditThe disk drive industry followed a different pattern. Industry practice, more thoroughly documented at Timeline of binary prefixes and continuing today, is generally to specify hard drives using prefixes and symbols with decimal meaning as described by SI. Unlike computer main memory, there is nothing in a disk drive that causes, or even influences, the capacity to be an integer multiple of a power of 1. For example, the first commercially sold disk drive, the IBM 3. It was introduced in September 1. In the 1. 96. 0s most disk drives used IBMs variable block length format called Count Key Data or CKD. Any block size could be specified up to the maximum track length. Since the block headers occupied space, the usable capacity of the drive was dependent on the block size. Blocks records in IBMs terminology of 8. The drive capacity was usually stated under conditions of full track record blocking. For example, the 1. Floppy disks for the IBM PC and compatibles quickly standardized on 5. K. The 3. 5 inch 3. KB and 7. 20 KB had 7. When the High Density 1. MB floppies came along, with 2. MB 2. 10 x 1. 03 1 0. In contrast, hard disk drive manufacturers used megabytes or MB, meaning 1. By 1. 97. 7, in its first edition, DiskTrend, a leading hard disk drive industry marketing consultancy segmented the industry according to MBs decimal sense of capacity. One of the earliest hard disk drives in personal computing history, the Seagate ST 4. Formatted 1. 0. 0 Megabytes. More precisely, the drive contains 4 heads or active surfaces tracks per cylinder, 3. This drive was one of several types installed into the IBM PCXT2. MB formatted hard disk drive. The factor of 3. 06 cylinders rather than 2. MB. Many later drives in the personal computer market used 1. Nor are drives required to have a number of active surfaces that is a power of, or even divisible by, two drives with e. All of these factors reduce the utility of the customary binary prefixes for expressing drive capacity. Today, the hard drive industry continues to use decimal prefixes for drive capacity as well as for transfer rate. For example, a 3. GB hard drive offers slightly more than 3. Operating systems such as Microsoft Windows that display hard drive sizes using the customary binary prefix GB as it is used for RAM would display this as 2. GB meaning 2. 79. B. On the other hand, Mac OS X has since version 1.