[comp.terminals] vt220

cheselka@cactus.org (Mike R. Cheselka) (04/02/91)

I have a vt220 by digital, the real thing, not a clone. What is the
'Compose Character' key for? How can I use it? Can I 'save' stuff to the
function keys so that I power up with Hayes AT commands on them? Are there
any roms out there for Japanese characters sets? More generally, would 
some kind soul send me some information about the differences between the
various vt### terminals? I always use the vt100 set up, how would vt220
be better? Can graphics be viewed, like gifs or bitmaps?
Any responses would be apreciated. I would esp. like encyclopedic amounts
of information :-)

conrad@tharr.UUCP (Conrad Longmore) (04/04/91)

In article <6171@cactus.org> cheselka@cactus.org (Mike R. Cheselka) writes:
>
>I have a vt220 by digital, the real thing, not a clone. What is the
>'Compose Character' key for? How can I use it? 

The 'Compose' key is for creating high-order ascii characters, and other
ascii characters not on the keyboard. To use it, you must operate the
terminal in an eight-bit environment, and be using the VT in VT220 mode.
Put simply, you compose an accented character by a two or three character
sequence, e.g. for A-umlaut you would type COMPOSE A ", for c-cedilla type
COMPOSE c , ... for GB pound sign it's COMPOSE l =, for Japanese yen it's
COMPOSE Y =. Most of the accented characters are fairly easy to guess once
you understand the principle of 'combining' the ascii characters.

>Can I 'save' stuff to the
>function keys so that I power up with Hayes AT commands on them?

The contents of the function keys are host-writable, but the VT220 loses the
settings when turned off. You could look at the ANSWERBACK field though.

>Are there
>any roms out there for Japanese characters sets? 

The character matrix on the VT220 is a bit too crude to allow much in the
way of Japanese, as the chinese root symbols that most of Japanese starts
words with are too complex to the represented properly. Terminals such as
the VT320 have more complex character matrices.

>More generally, would 
>some kind soul send me some information about the differences between the
>various vt### terminals? I always use the vt100 set up, how would vt220
>be better? Can graphics be viewed, like gifs or bitmaps?

The VT220 is a text-only terminal. A quick guide as to the main differences
between the VT terminals follows:

Terminal	Extended Mono	Colour	Redefinable  Refresh Dual Host
		keybd?	 Graph? Graph?  characters?  rate    (2 sessions)?

VT52		No	 No	No	No	     60Hz    No
VT100		No	 No	No	No	     60Hz    No
VT125		No	 Yes	No	No	     60Hz    No
VT220		Yes	 No	No	Yes	     60Hz    No
VT230		Yes	 Yes	No	Yes	     60Hz    No
VT240		Yes	 No	Yes	Yes	     60Hz    No
VT320		Yes	 No	No	Yes	     60Hz    No
VT330		Yes	 Yes	No	Yes	     60Hz    Yes	**
VT340		Yes	 No	Yes	Yes	     60Hz    Yes	**
VT420		Yes	 No	No	Yes	     70Hz    Yes	**
VT1000		Yes	 Yes 	(Monochrome X-windows terminal)
VT1200		Yes	 Yes	(Monochrome X-windows terminal)		**
VT1300		Yes   	 No	Yes (Colour X-windows terminal)		**

All VT100-400 terminals are ANSI X3.41-1977 and X.3.64-1979 compliant.
VTx30 and x40 terminals use Regis graphics, which can provide bitmapped
displays. The VT340 display is very similar to EGA. Terminals marked with
** are current digital terminals.


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