VT220 Emulation in Kermit 95

Kermit 95 includes a fairly comprehensive VT220 emulation including features rarely implemented by other terminal emulators such as soft character sets (soft fonts / dynamically redefined character sets) and smooth-scroll.

VT220 is also Kermit 95s default emulation as it is present in most hosts terminfo database. You can also choose from one of two VT220 emulation options by selecting either vt220 or vt220pc from the drop-down list on the toolbar (K95G) or using the SET TERMINAL TYPE command.

Key Map

The VT220 and VT220PC terminal types differ only in their default keymap:

For more on the keymap used by Kermit 95s VT220 emulation, see: Kermit 95 VT220 / VT320 Function Key Mapping

Differences in K95s VT220 emulation

Any differences between Kermit 95s VT220 emulation and a real VT220 except for those noted below are likely a bug.

Functionality

The following functions are implemented differently in Kermit 95 vs a real VT220:

132 Column Mode

Instead of using a condensed font in 132-column mode, Kermit 95 changes the window size.

VT100 Confidence Tests (DECTST)

Kermit 95 does not implement this function

Interlaced Video Mode (DECINLM)

Kermit 95 does not implement this mode

Settings

VT settings map on to Kermit 95 settings as follows. Note that Kermit 95s defaults for some settings differ from that of a real VT220, and Kermit 95 lacks equivalents of some settings.

Set-Up Screen	VT Setting	VT220 Default	K95 Default	K95 Setting	Notes
	On Line/Local	On Line			K95 does not implement a Local mode
	Clear Display	n/a (action)		CLEAR TERMINAL-SCREEN ALL
	Clear Comm	n/a (action)		CLEAR DEVICE-AND-INPUT CLEAR KEYBOARD-BUFFER	These commands aren't an exact equivalent. They don't cancel or reset printing or abort any escape sequences in progress.
	Reset Terminal	n/a (action)		\Kreset	Use Reset Terminal from the Actions menu, or enter \Kreset at the command screen.
	Keyboard	North American
Display	80/132 Columns	80 columns		SET TERMINAL WIDTH	K95 allows arbitrary widths to be set
	Control Representation	Interpret Controls			K95 does not provide a command for togging this option.
	Auto Wrap	Off	On	SET TERMINAL WRAP
	Scroll	Smooth	Jump	SET TERMINAL SCROLL-MODE
	Text, Screen	Light Text, Dark Screen		SET TERMINAL COLOR TERMINAL
	Text Cursor	Cursor		SET TERMINAL CURSOR
	Cursor Style	Block	Underline	SET TERMINAL CURSOR
General	Mode	VT200 Mode, 7-bit	VT200 Mode, 8-bit	SET TERMINAL TYPE SET TERMINAL BYTESIZE
	VT100 Mode Terminal ID	VT220		SET TERMINAL TYPE	Dedicated VT100, VT101 and VT102 emulations are available
	User Defined Keys	Unlocked	Locked	SET TERMINAL LOCK-KEY-DEFINITIONS	Locked by default in K95 for security
	User Features	Unlocked			K95 does not support this feature
	Character Set Mode	National		SET TERMINAL CHARACTER-SET
	Keypad	Numeric		SET TERMINAL KEYPAD-MODE
	Cursor Keys	Normal		SET TERMINAL ARROW-KEYS
	New Line	No New Line		SET TERMINAL NEWLINE-MODE
Communications	Transmit	4800		SET SPEED	K95 does not allow setting separate transmit/receive speeds
	Receive	Transmit
	XOFF	XOFF at 64		SET FLOW	K95 doesn't support setting when XOFF occurs. RTS/CTS flow control is also supported.
	Bits	8		SET TERMINAL BYTESIZE	K95 uses the terminal bytesize for serial data bits
	Parity	No Parity		SET PARITY
	Stop Bit	1		SET STOP-BITS
	Local Echo	Off		SET LOCAL-ECHO
	Port	EIA port, Data Leads Only		SET LINE
	Disconnect, ___ Delay	Disconnect, 2s Delay			K95 doesn't allow changing the disconnect delay.
	______ Transmit	Limited Transmit	Unlimited Transmit	SET OUTPUT PACING	K95 allows setting a per-output-character delay
Printer*	Speed	4800		SET PRINTER /SPEED:
	Mode	Normal		SET TERMINAL PRINT
	Bits	8			K95 does not support this setting
	Parity	None		SET PRINTER /PARITY:
	Stop Bits	1			K95 does not support this setting
	Print...	Full Page			K95 does not support this setting
	Printed Data Type	Print National Only		SET PRINTER /CHARACTER-SET:
	Print Terminator	Terminator = FF	No Terminator	SET PRINTER /END-OF-JOB-STRING:
Keyboard	Typewriter/Data Processing Keys	Typewriter			K95 does not support this setting or the Data Processing Keys option
	Caps/Shift Lock	Caps Lock			K95 does not support this setting or the Data Processing Keys option
	Auto Repeat	On			K95 only supports changing this setting via DECARM
	Keyclick	On	Off	\Kkeyclick	This setting is available from the Actions menu in K95G, and can be toggled via the \Kkeyclick Kverb (you can enter it as a command)
	Margin Bell	On	Off	SET TERMINAL MARGIN-BELL
	Warning Bell	On		SET BELL
	Break	On			The break key can be unmapped with SET KEY
	Auto Answerback	On
	Answerback			SET TERMINAL ANSWERBACK MESSAGE	K95 does not support setting arbitrary answerback messages
	Answerback Concealed				K95 does not support this setting
Tab	Clear All Tabs				K95 does not implement commands for manipulating tab stops. Tab stops can only be manipulated via control sequences.
	Set 8 Column Tabs
	Set Tab Stops

* K95 also supports printer connectivity options besides serial. See Printer Setup and Troubleshooting for more information on printing options.

If you want Kermit 95s VT220 emulation to use similar defaults to a real VT220, you can put the following in your k95custom.ini so that they run automatically when the VT220 or VT220PC terminal emulations are chosen.

    def tt_vt220 {
        set terminal wrap off
        set terminal scroll-mode smooth
        set terminal color terminal lgray black
        set terminal cursor full on
        set terminal bytesize 7
        set terminal lock-key-definitions off  ; Enable DECUDK - a security risk
        set terminal sgr-colors off            ; A real VT220 doesn't support color
    }

    def tt_vt220pc {
        tt_vt220
    }

    ; K95s terminal emulator is initialised to VT220 before any startup scripts
    ; are run, so this is required to ensure tt_vt220 runs on startup.
    if equal \v(terminal) vt220 tt_vt220

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