VT52v2 Documentation
--------------------

By Dave Jansen

VT52 Terminal Emulator v2.0

The following 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 of the characters sent.  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 can easily display a screenful of information at a time.
Another method to try to stop loosing characters is to set the IOPAR to
use XON/XOFF, but so far I have not been able to get this to work.

Directions
1.  VT52 - execute the program
2.  if you wish to do a file transfer, quit (press ATTN) and perform the
    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	/
	\	}	>	)	]

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

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

		=	?	_	|
9	ATTN	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.

I have added the capability to change the font size.  This will make screen
sizes of 6x22, 8x22, 10x22, 10x26, 10x33.  It will be necessary to edit the
program and change the csize, ch, and cw variables to one of the following
formats:

6x22
csize	3
cw	6
ch	10

8x22		default value
csize	2
cw	6
ch	8

10x22
csize	1
cw	6
ch	6

10x26
csize	1
cw	5
ch	6

10x33
csize	1
cw	4
ch	6
