Handy Facts - InfoTech, Communications, & Networking

Macfarlane's law of communications inequity

You can talk faster than you can type, but you can't listen as fast as you can read.

Alternate Positive Version: You can talk faster than you can type, but you can read faster than you can listen. (Read more about Macfarlane's Law on the Wikipedia.)

How many nines in your uptime? The precision of decimal time

Uptime in percentage of timeTime down implied by the uptime
 Per WeekPer MonthPer Year
99.0 %1 h 41 m7 h 12 m3.65 days
99.9 % 10.1 m 43.2 m 8.75 hrs
99.99 % 1 m 4.5 m 52.5 m
99.999 % 6 sec 26 sec 5.25 m
99.9999 %   2.5 sec 31 sec
99.99999 %     3 sec

New data in the world

Between 1 and 2 exabytes per year
According to a study produced by the faculty and students at the University of California at Berkeley, the world produces about 5 exabytes of unique information per year (an exabyte is a billion gigabytes). Email generates about 400,000 terabytes of new information each year worldwide.
Using the disk transfer rate of 100 Mbits per second (a typical value these days), it would take over 12,675 years to save 5 exabytes to a single disk.

Chronology of Programming Languages

The following table shows the first year of working implementations of each major language.

      YearLanguage
      1957FORTRAN
      1958ALGOL 58
      1959LISP
      1961COBOL
      1962SNOBOL
      1964RPG
      1964BASIC
      1967APL
      1968LOGO
      1971Pascal
      1972Smalltalk
      1972C
      1978SQL
      1983C++
      1985Postscript
      1987Perl
      1987Mathematica
      1988Tcl
      1991Python
      1993Ruby
      1994PHP
      1995Java
      1997JavaScript
      2000C#
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