Project DisplayAFile
Overview
The scientists and engineers who created the first digital computers wanted machines that could compute mathematical answers quickly and accurately. For this reason, a measure of merit to rank early machines was created by these same scientists and engineers : How quickly can a given machine add two numbers together and place the answer in memory? These were not integers (that calculation was too simple). The numbers were floating-point, or as we call them today, floats (base 2 arithmetic). Most manufacturers discovered early that floating-point arithmetic would require a very large word size, on the order of 64, 128, or even 256 bits. So even the earliest CPUs were equipped with methods to concatenate groups of smaller size words. While some early machines claimed speed as their forte, others claimed accuracy. The smaller the total word size, the faster the machine could add two numbers. The larger the total word size , the more accurate the answers became.
Since three bits can contain only eight different numbers, it took four bits (16 numbers) to contain one base 10 number. A typical 32-bit word used for arithmetic purposes reserved 24 places for the mantissa (the number written in base 2) and only eight places for the exponent. This layout for floating-point numbers allowed a representation of numbers from - 3.4 x E38 (10 to the 38th power) to +3.4 x E38. But the 24-place mantissa in base 2 only created about six digits of accuracy (in base 10). The IEEE Standards Committee immediately declared that a double data type should be included in computers, with a 53-bit mantissa and an 11-bit exponent. With the double the mantissa size went from 24 to 53 bits, and the number of digits of accuracy (in base 10) went from 6 or 7 to 15 or 16. The double serves 99 percent of the world for accuracy purposes today.
For those who wanted even greater accuracy (like NASA and astronomers), machines like the Cray were built with a basic arithmetic word size of 128 or 256 bytes.
EAN: 2147483647
Pages: 129
- Step 1.1 Install OpenSSH to Replace the Remote Access Protocols with Encrypted Versions
- Step 3.1 Use PuTTY as a Graphical Replacement for telnet and rlogin
- Step 5.2 Troubleshooting Common OpenSSH Errors/Problems
- Step 6.1 Port Forwarding
- Step 6.2 Using Port Forwarding Within PuTTY to Read Your E-mail Securely
If you may any questions please contact us: flylib@qtcs.net