Acronyms and Abbreviations

While I was looking for some ideas for the next Linux Buzz, a banner ad on the Linux Journal site momentarily confused me. It is the banner for Code Fusion and it was talking about an IDE. While I visualized an IDE disk drive only momentarily, I realized that lots of people could be confused by many of the acronyms and abbreviations we use. So, that quickly became my subject for the week.

As IDE inspired this column, let's start there. When talking about an interface to a disk drive, CD-ROM or tape drive, IDE is an abbreviation for Integrated Drive Electronics. IDE disks replaced MFM (Manchester Frequency Modulation) and RLL (Run Length Limited) disks. Clearly, MFM and RLL were pretty useless terms for the computer user. Both these terms referred to the way data was stored on the disk. Data encoding was done by the controller card. The significance of IDE was that the data encoding was moved from the controller card to the disk drive itself.

The other IDE? The one that was in the banner ad. Integrated Development Environment. This is where you can write and test your code without leaving one program. For me, this is an alternative to edit with vi, compile and link with cc, execute and then possibly debug with gdb. For Emacs users, they will say that Emacs is an IDE.

My personal favorite abbreviation is ATM. Most people on the planet think it means "place to get cash". Many of these people don't even know it stands for Automatic Teller Machine. If they did, why would they say they are going to an ATM machine?

Two more meanings: Asynchronous Transfer Mode and Adobe Type Manager. Asynchronous Transfer Mode refers to a protocol for transferring data. And, of course, Adobe Type Manager is a program that manages PostScript and other fonts.

How about those communications terms like PPP, SLIP, DSL and ISDN? PPP and SLIP are communications protocols. DSL and ISDN are types of communications services.

PPP stands for Point-to-Point Protocol. It is the most common protocol for modem connections. It allows you to appear, to the rest of the Internet, just like any other connected host. PPP has mostly replaced SLIP (Serial Line Internet Protocol) as the standard protocol used for these connections. The reason is that SLIP "just happened" and lacks both capabilities and standards.

DSL (Digital Subscriber Line) and ISDN (Integrated Services Digital Network) are both services that allow you to digitally connect to different sites. DSL is the newer service, offering higher speeds but less flexibility. With DSL service, you receive a constantly connected link to another site, generally your ISP. Minimum speed is 256Kbps with speeds of multiple megabits available. <o> ISDN differs in that it is a dial-up connection much like a standard telephone. A BRI (Basic Rate Interface) ISDN line makes two 64Kb channels available to the user. The two channels can be used together for a higher data rate. Besides speed, ISDN offers extremely fast setup (connect) times making it idea for such services as credit card verification.

Oops, I said "modem" above. That's modulator/demodulator. Modulator refers to the operation of encoding digital data into an analog format for transmission over an analog (voice) line. Demodulator is the operation at the other end to recover the data back into its digital form. While commonly used, there is no such thing as a "DSL modem". DSL is digital, so there is no modulation process involved. Generally you are talking about a DSL router.

Oh, "router". Caught again. A router allows you to connect networks together in an intelligent fashion. By "intelligent fashion", I mean that a router does not just supply an electrical connection between equipment (a hub does this) but it takes action based on the, well, data.

At this point I feel I have gotten myself into enough trouble. In the last paragraph where I said "data" I really wanted to say "packets". But then I would have to talk about IP and TCP and, well, you get the idea.

Linux Journal has introduced a lot of new terms. We try our best to define them when we introduce them, but searching through six years of magazines may not be the best way to look up these terms. Would a glossary, printed or on-line, be of use? Let me know.