- Analogies

This is the place to go whenever you don't understand something and you would like a comparison to something more familiar to you. Simply ask a question and we will respond with an analogy for it.

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MIDI - Telephones offer a good analogy to how MIDI works. Phone cables connect phone devices together, while MIDI cables connect MIDI devices together. You might be inclined to rephrase the previous sentence to read "Phone cables connect phones together..." but that would be limiting our choices given the variety of devices that are connected to a phone line today. Fax machines, Modems, and Answering Machines are all "Phone-line compatible" devices, meaning they have the appropriate connectors to be connected to phone lines. In similar fashion, the equivalent "phone" of MIDI is the electronic piano. The range of devices that can now be controlled with MIDI includes recording equipment, digital audio playback devices, lighting consoles, home automation, animated characters, audio mixing consoles and more.

Protocol / Standard - A protocol is simply a set of actions that collectively become a "way of doing something". Let's look at the protocol for "making a phone call". A simplified protocol states that you would do the following:

1. Dial a phone number.

2. Wait for "Hello"

3. Ask "Can I speak to [friend]"

4. Wait for response.

5. Talk to [friend]

A modem protocol is basically a variation on the phone call above -- with the different tones emitted from the modem representing the steps of the setup. The modem is basically dialing up another modem and trying to establish the basis for a conversation.

Once a conversation (a connection) has been established (using the imaginary "Hello" protocol), then services using other protocols can begin to run -- i.e. the actual function of the conversation can begin.

For instance, if you transfer a file, you are using a protocol which says how the data will be copied. It's as if I said, after establishing my phone conversation, "OK now I'm going to give you some directions to my house using the 'Line Repeat' protocol." This fictitious protocol states that after each line of data I speak into the phone, I want it repeated for verification.

Maybe later, I get tired of hearing my same words repeated over and over so I make a new version of the 'Line Repeat' protocol called the 'Line Acknowledge' protocol. This protocol states that the person on the other end of my phone conversation need only say "Uh huh..." after each line. That allows me to know that I can move on to recite the next line.

A standard is simply the most widely known and used protocol (or variant of a protocol) for a given activity. In the example above, I suppose the standard (when writing down directions given over the phone) would be to use 'Line Acknowledge' protocol. You might also use a variant of 'Line Acknowledge' protocol that has optional spell checking enabled for verifying strange street names... Any way, hopefully, you get the idea...