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 time | Time down implied by the uptime |
|---|
| | Per Week | Per Month | Per Year |
|---|
| 99.0 % | 1 h 41 m | 7 h 12 m | 3.65 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.
| Year | Language |
|---|
| 1957 | FORTRAN |
| 1958 | ALGOL 58 |
| 1959 | LISP |
| 1961 | COBOL |
| 1962 | SNOBOL |
| 1964 | RPG |
| 1964 | BASIC |
| 1967 | APL |
| 1968 | LOGO |
| 1971 | Pascal |
| 1972 | Smalltalk |
| 1972 | C |
| 1978 | SQL |
| 1983 | C++ |
| 1985 | Postscript |
| 1987 | Perl |
| 1987 | Mathematica |
| 1988 | Tcl |
| 1991 | Python |
| 1993 | Ruby |
| 1994 | PHP |
| 1995 | Java |
| 1997 | JavaScript |
| 2000 | C# |
| 2007 | Clojure |
| 2009 | Go |
| 2012 | TypeScript |
| 2014 | Swift |
|