HIR Issue 4: An introductory guide to those mysterious green-screened monsters
Dumb terminals have been used with computers since the advent of mainframe computers. All that a dumb terminal is, is an input/output device that is attached to a larger, more powerful computer via a serial connection, modem, or other network connection. There have been many different kinds of terminals created since the idea first came into play. Some of the more popular ones were the Televideo Terminal, and Digital (DEC)'s VT 100, 102, and 400 terminals. You can still find these terminals in libraries, stores, colleges, and some offices. Essentially, all that these terminals contain is a CRT (Screen), a keyboard, and inside the body of the monitor, is a circuitboard, which contains some ROM chips with some hard-coded programs (This included information for some specific emulation functions, the setup program, and the standard boot-up, connection, and self-test functions), as well as a small amount of RAM (used for Input, Communication, and print buffers), but there is also an area of EEPROM. This, in conjunction with the setup program, is going to be a major part of this article.
Why would you want to mess with these terminals?
Well, there are many reasons why one would want to mess with them, or at least get familiar with them. At stores, you might see one of these just out in the open, and unattended. Some stores i know of (such as Comp-USA), they have the terminals on the sales floor so that sales people can look up prices, quantity in-stock, and other information about the merchandise, in case a customer has a question, or if they can't find what the customer wants (which happens so often that you stand a better chance of finding it yourself). Now, if only you knew how to use it... Well, every place has their own software, and i can not spend my time telling you the ins and outs of each individual software. I've also seen these terminals in libraries, used for electronic card catalogs. Dumb terminals are easily distinguished by either a nasty Green, amber, or white/grey screen, attached directly to a keyboard. You can find out about each terminal and what kind of software is being run once you find one of them logged in.
You need to find the set-up hotkey sequence. Some of the DEC terminals just use F3. (if there's an F-key or other non-alpha-numeric key that seems to have been torn off, there's a good chance that's the one you're looking for. This was the case in a blockbuster video i was at a few weeks ago, where they had a terminal up and running for Blockbuster patrons to look up rental availability, new releases, up-and coming rental release dates, etc). On Televideo Terminals, There's always (or at least I've always seen) a key close to the upper right hand corner of the keyboard, kind of where the F-keys are, and it's labeled:
Set Up
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<something> I can't remember what the option on the bottom of the key is, but you just have to hit the Shift Key, and that key at the same time.
The Set-Up Menus
These vary drastically from one terminal to the next. You're almost always guaranteed to find out more about the software that the establishment you're messing with is using, just by looking at the programmed macros. If you're feeling evil, write the settings down, and change them on that terminal. You can usually change some normal system settings, such as Reverse Video mode, Connection Speed, printing (if there's a printer), and in some cases, you can access a log of keystrokes (hee hee!). A very few terminals allow the user to define their own custom emulation settings, allowing an advanced, and properly informed user to set a Televideo terminal to handle VT, 3270, Prism, and many others.
Dumb terminals are great if you just want to hit some dial-up unix shell accounts or get on bulletin boards. You can usually hook a modem up directly to it and go to town. This works best with VT series terminals, because the VT-100 + emulation settings are very similar to the ANSI codes that many BBSes use. If you don't have a VT terminal, most unix systems allow the user to define the terminal type, and it will slip into that emulation mode.
This article doesn't really cover many specifics, other than to point out that these pieces of equipment which have been labeled completely obsolete, still have value and function, and not only to the hacker. I wish it was possible for me to show exactly how to get into setup (and what you can do once you're in there) on as many different models as possible, but I can't, simply because it's different for each brand, and between models. Sometimes it's just fun to hack around trying to find the cool little "secret" menus.
