| Word or
Term |
Description or
Explanation |
| UART |
Universal Asynchronous Receiver/Transmitter - a
component that manages the reception/transmission of serial data from/to the
outside world - it converts it to parallel data suitable for use within the
computer |
| ucb |
(University of California at Berkeley) - it
refers to a variant of the POP3 email server that doesn't support command
buffering - the suffix /ucb disables command buffering, so ANT's !InetSuite has
to wait for the response of a single command before sending the next single
command |
| when mail from "mail.surfaid.org" stopped
working, ANT recommended changing to "mail.surfaid.org/ucb", whereupon the
flood-gates opened |
| UDP |
User Datagram Protocol - an alternative to TCP,
used in cases where reliability is considered unimportant, or where a
connection-oriented dialogue is not required - each datagram is fired into the
network as a single IP packet, and if it gets lost before reaching its
destination, then tough luck |
| Unix |
the operating system used by most of the
computers that provide services on the Internet - unlike a personal computer
system like RISC OS, Unix is designed to provide access to many users at once
and almost always comes with built-in TCP/IP and so it has become very popular
as a network machine - the main thing to watch out for when connected to a
computer running Unix is that it allows very long file names that are case
sensitive, i.e. Fred, fred and FRED are different - the reason most Internet
servers run one of the many varients of Unix is that the Internet Protocol
Suite was developed in the academic community which also embraced Unix in the
seventies - Unix was not only freeware, but also offered more features than
anything else available - also, because it had its own system programming
language ('C'), it was the ultimate 'mix-and-match' operating system and a
programmer's paradise |
| Upload |
transfer files or messages from your computer
to a distant computer |
| UPS |
Uninterruptable Power Supply - a device
connected between the mains supply and the computer, which provides a short
term supply in the event of a power failure - this gives you a few minutes to
shut down your applications and save your data in an orderly fashion (well, a
bit more orderly than phut and a black screen!) |
| URL |
Uniform Resource Locator - a universal
addressing scheme for Internet resources - the idea was introduced at the same
time as the World Wide Web, and most web browsers support it fully - the
general format is:
protocol://machine.site/directory/filename
For
example:
http://www.acorn.co.uk/acorn/Home
ftp://ftp.acorn.co.uk/pub/documents/pricelist
the
first example is a hypertext page fetched from Acorn's World Wide Web server
using HTTP, and the second is a file fetched from Acorn's FTP server, using
anonymous FTP - other protocols supported include 'gopher:' and 'news:' |
| USB |
Universal Serial Bus - a bus-bar system
developed by Intel and Microsoft to allow connection of up to 127 peripherals
daisy-chained, internally or externally, giving a quick, simple, expansion
potential for the computer - USB will allow 'hot' connection, i.e. without the
need to power down the system while making the connection |
| Usenet |
the term used to refer to the Internet news
network - Usenet is not a real physical network as such (although it was once,
apparently) - it is a virtual network of news servers which communicate via the
Internet - there is no central Usenet site - instead, news propagates around
the world as each server connects to its news feed (another news server) and
exchanges new articles with it - hence, no single server ever holds the entire
contents of any given newsgroup |
| User-id |
UID - a name or number used to identify a
specific individual user when accessing a remote system - often has to be
followed by a password |
| User name |
on most host systems, the first time you
connect you are asked to supply a one-word user name - this can be any
combination of letters and numbers - it is a unique identifier that is linked
to a UID in the Unix operating system(s) - this is done so that people don't
have to go around and remember their UID |
| User port |
an 8-bit parallel interface which can be used
for the input and/or output of data - commonly used for connecting to concept
keyboards and for doing control experiments |
| UUCP |
Unix to Unix Copy Program - a protocol used on
dialup connections to transfer files and execute commands - this can be used to
let the server call the clients or vice versa and is extremely efficient on low
bandwidth connections - this is the original protocol used to transport NetNews
and also the original protocol on Usenet - there are actually two UUCP ports
for the RISC OS: one is the port of Taylor UUCP and the other is the port of
some other UUCP implementation |
| Uudecode |
a program that takes a uuencoded file (see
next) and recreates the original binary file(s) |
| Uuencode |
a coding system by which binary data can be
transmitted over a text-only email system - Uuencode takes data using bytes in
the range [0-255] and encodes it to a limited range of ASCII codes, usually in
the range [32-127] - as a result, the encoded data can take up more space than
the original binary file |