The remainder of this demonstration shows the emulation in action:
(To stop this demo at any time, type Esc or Command-period.)
------------------------ Press any key to continue: ------------------------
HVT52 Emulation mode:
In its simplest form, the VT100 serves as a direct replacement for
the well-known VT52. The screen format is 24 lines of 80
columns, in lower and upper case, and the VT100 will accept the
complete set of VT52 escape sequences, including...
?2lCursor stepping...CCCCCCCCCCCCCCCCCCCC...to the right...BBBBBB...down...DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD...back to the left...AAAA...and up...
HJY#%We have direct cursor addressingHTo home position...Y*D...or...Y,H...anywhere else...Y.L...on the screen...
We have partial erase; we can erase the rest of a line...DDDDDDDDDDDDDDDDDDDDDK
or the rest of the screen...
AA
JAKHFrom here at the home position we can erase the whole screen...HJThe keyboard alternatives exist, too, including
alternate keypad and cursor control keys.
We even have a set of special characters.
F !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOP
Beyond its capabilities as a VT52 emulator, the VT220
implements a full set of ANSI compatible controls,
and a set of features never before found in a DEC terminal.
It does, of course, have the normal cursor stepping.
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC...to the right...DDDDDDDDDDDDDDDDDDDDDDDDDDDDDD...back to the left...BBBBBB...down...AAAAA...and back up...
...but beside the unit cursor stepping, it has relative
cursor spacing, by stepping with a parameterized move...
from the margin...C...way right...D...back to the left...A...straight up...B...and down again...
...all in a trice.
HAbsolute direct cursor addressing is available in three forms.
The parameterized ANSI sequences offer two commands.
15HEach is implemented to allow the user freedom of choice.The third is the "save and restore cursor" command pair.1HThe available erase commands are much more versatile
than the comparable VT52 modes.
From the current cursor position,
we can erase to the end of the line. (this part, for example).
...or we can erase to the start of the line (as the line above).
or the entire current line from any point within it.D1HThe entire screen can be bounded in the same manner,
and we can erase to the end of the screen from the cursor...
...from the start of the screen to the cursor...
AA...or the whole screen at once...
HSeveral character sets may be resident in the VT100.
The normal set is the USASCII set of letters and graphics...