VT52 Documentation
------------------

By David D Jansen

This is a DEC VT52 terminal emulator for the HP48SX.  It emulates
every vt52 command except for the Keypad mode (kind of redundant on the HP)
and the special graphics characters (perhaps in a latter version).  The one
drawback, like other communication programs for the HP48, is speed.  Because
it is slow after the recieve buffer (which is 256 characters long) fills up,
it looses the rest.  Buffering the receive buffer will not work since at
9600 baud the buffer fills up in about 3 hundredths of a second.  Nevertheless
Since fewer than 256 characters can fit on the screen at one time, it is
functional.  If enough interest shows, an assembly version could be written.
Another possibility is to set the IOPAR to enable XON/XOFF.  So far I have
not been able to get this to work.

Directions
1.  execute the program
2.  if you wish to do a file transfer, quit and do the usual Kermit transfer,
    then just run the program again to continue.

Keyboard

The keyboard of the HP48 was redefined as the following.

	1	2	3	4	5	6

	A	B	C	D	E	F
1	a	b	c	d	e	f
	^A	^B	^C	^D	^E	^F

	G	H	I	J	K	L
2	g	h	i	j	k	l
	^G	^H	^I	^J	^K	^L

	M	N	O	P	Q	R
3	m	n	o	p	q	r
	^M	^N	^O	^P	^Q	^R

	S	T	U	V	W	X
4	s	t	u	v	w	x
	^S	^T	^U	^V	^W	^X

	ENTER	Y	Z
5	ENTER	y	z	DELETE	BACKSPACE
	ENTER	^Y	^Z

		{	<	(	[
6	ESCAPE	7	8	9	/
	\	}	>	)	]

	CAPS LOCK	$	%	^	&
7	SHIFT	4	5	6	*
	QUIT	CHR(28)	CHR(29)	CHR(30)	CHR(31)

		,	~	`	'
8	CONTROL	1	2	3	-
	BREAK	;	@	#	"

		=	?	_	|
9	ATTENTION	0	.	SPACE	+
		CHR(0)	!	TAB	:

The labels above the numbered row is the left shift key.  Labels on the
same line as the numbers are the default values and labels under the
numbered lines are the right shift values.
The numbers are the row and column of the keyboard.  Quitting by pressing ON
leaves the port open and is not necessary even to stay online.
All 128 ASCII characters are accessible from the keyboard.  I suggest getting
a template and writing the above table on it for easiest use.
