HP ASCII and Trigraphs

HP-ASCII and Trigraphs

As mentioned elsewhere, HP calculators use a non-standard version of ASCII which does not directly map to the Macintosh's ASCII based disk file system and is difficult to input on a standard keyboard. Fortunately, HP also provides a work around for these limitations: When you send or receive HP objects as text files, HPConnect will translate these special characters into "trigraphs" - groups of three standard ASCII characters. These trigraphs can be readily input with any standard keyboard and even a simple text editor:

ASCII Code	Trigraph	Description	ASCII Code	Trigraph	Description
92	\\	Backslash	128	\<)	Angle
129	\x-	Mean (bar-x)	130	\.V	Inverted Triangle
131	\v/	Square Root	132	\.S	Integration
133	\GS	Sigma	134	\\|>	Solid Triangle
135	\pi	Pi	136	\.d	Derivative
137	\<=	Less or Equal	13	\>=	Greater or Equal
139	\=	Not Equal	140	/\Ga	Alpha
141	\->	Right Arrow	142	\<-	Left Arrow
143	\\|v	Down Arrow	144	\\|^	Up Arrow
145	\Gg	Gamma	146	\Gd	Delta
147	\Ge	Epsilon	148	\Gn	Nu
149	\Gh	Theta	150	\Gl	Lambda
151	\Gr	Rho	152	\Gs	Lower Case Sigma
153	\Gt	Tau	154	\Gw	Omega
155	\GD	Delta Triangle	156	\PI	Upper Case Pi
157	\GW	Upper Case Omega	158	\[]	Square Dot
159	\oo	Infinity	171	\<<	Start Program
176	\^o	Degree	181	\Gm	Micro
187	\>>	End Program	215	\.x	Multiplication
216	\O/	Phi	247	\:-	Division
All others		\### where "###" is the three digit ASCII code of the character. For example, the euro symbol is "\160"

HP ASCII File Format

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An HP formatted text file has two main attributes. First, it probably uses trigraphs to indicates special HP ASCII symbols such as infinity and right arrow. Second, it begins with a special one line header that tells the HP what calculator settings should be used to interpret the file.

The one line header has the form "%%HP: T(t)A(a)F(r);" where t, a, and r are the translation mode, angle mode and radix mode:

Translation Mode		Angle Mode		Radix Mode
Value	Description	Value	Description	Value	Description
0	No translation	D	Degree Mode	.	Period is used as the decimal point: 123,456.789
1	Translate linefeeds (ASCII #10) to carriage-return + linefeed (#13 #10)	G	Gradian Mode	,	Comma is used as the decimal point: 123.456,789
2	Translate some special characters. (HP ASCII characters less than 160 are translated into trigraphs)	R	Radian Mode
3	Translate all special characters.

Note that while HPConnect can read files written with any translation mode and send them to the HP, when accepting files from the HP it will always uses translation mode #3.

To use these trigraphs to write HP calculator software on your Mac, use your favorite text editor and use the trigraphs whenever you need a special HP symbol or character. To copy the software to the HP, make sure the text file has a proper header (for example, "%%HP: T(3)A(R)F(.);"). Next, start HPConnect normally,select ASCII transfer mode and send the file to the HP. When the HP receives the file, it will attempt to compile it into an HP object.

NOTE: Please note that if the ASCII file is not syntactically correct, the HP calculator will reject it. This is a limitation of the HP, not HPConnect.

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