hp91a

Model:	-91A

General:
	Name:			Scientific Portable Printing Calculator
	Code-Name:		Felix (Topcat?)
	Family:			Topcat
	Logic:			RPN
	Features:		scientific
	Firsts:			Topcat
	Introduction:
		Date:		1976-3-1
		Price:		$500
	Discontinuation:
		Date:		1979-01-01
		Price:		$325 (price change 1977-04-01)
	Production-Run:		?

Display:
	Type:			LED, 7 segment
	Size:			1 line x 15 chars
	Number-Formats:		sign, 10 mantissa, ., exp sign, 2 exp
	Annunciators:		red light for low battery

Data:
	User-Visible:
		Smallest:	1E-99
		Largest:	9.999999999E99
		Signif.-Digits:	10
	Internal:
		Smallest:	1E-99
		Largest:	9.999999999E99
		Signif.-Digits:	10
	Data-Types-and-Sizes:	real, 7 bytes

Memory:
	Named-Registers:	X, Y, Z, T, Last x, 0-9, .0-.5
	Flags:			none
	Register-Usage:		R.0	\GSn
				R.1	\GSx
				R.2	\GSx^2
				R.3	\GSy
				R.4	\GSy^2
				R.5	\GSxy
	Numbered-Registers:	16
	Program-Steps:		none
	Program-Editing:	none
	Program-Display:	none
	User-RAM-Bytes:		147
	Total-RAM-Bytes:	?
	ROM-Bytes:		?
	Machine-State:		prefix key state
				stack lift enable
				display mode
				registers
	File-Types:		none

Physical:
	Technology-Used:	?
	Processor:		?
	Chip-Count:		?
	Power-Source:		custom battery pack, A/C
	Continuous-Memory:	no
	Expansion-Ports:	none
	I/O-Ports:		thermal printer, 17 columns?
	Clock:			none

	Length:			?
	Width:			?
	Height:			?
	Weight:			?
	Temperature-Range:
		Operating:	0 to 45 deg C
		Charging:	15 to 40 deg C
		Storage:	-40 to 55 deg C

Keyboard:
	Switches:		OFF / ON
				MAN / ALL / NORM
				DEG / GRD / RAD
	Shift-Keys:		gold, gold, below
	User-Defined-Keys:	none

Key-Arrangement::

              ** ** ** *****

              ***** ** ** **

** ** ** **   ** ** ** ** **

** ** ** **   ** ** ** ** **

** ** ** **   ** ** ** ** **
                          **
** ** ** **   ***** ** ** **


Key-Labels-Base-Keyboard::

					x<>y	Rv	R^	PRINT x
					ENTER^		CHS	EEX	\:-
	 2	 x
\v/x	x	y	1/x		STO	7	8	9	x
SIN	COS	TAN	P->R		RCL	4	5	6	-
%	%\GS	y^	R->P		CLx	1	2	3	+
 x
e	LN	\GS+	[]		0		.	FIX	+

Key-Labels-gold-gold-below::

					[]	[]	[]	[]
					LIST:STACK------REG-----\GS	CL REG
H.MS+	H.MS-	->H.MS	H.MS->		\pi	[]	[]	[]	CL \GS
   -1	   -1	   -1
SIN	COS	TAN	s		LAST x	[]	[]	[]	[]
\GD%	N!	L.R.	x-		CLEAR	[]	[]	[]	[]
  x
10	LOG	\GS-	[]		[]		ENG	SCI	[]

Programmable-Operations::

none

Non-Programmable-Operations::

%		percent of
%\GS		percent of total
+		addition
-		subtraction
->H.MS		convert to hours,minutes,seconds
0-9, .		enter digit or decimal point
shift 0-6	clear shift
1/x		reciprocal
10^x		common exponentiation
CHS		change sign
CL REG		clear the registers
CL \GS		clear the statistics registers
CLEAR		clear the calculator
CLx		clear X
COS		cosine
COS-1		arc cosine
EEX		start an exponent, 1 not required
ENTER^		enter
e^x		natural exponentiation
FIX 0-9		fixed decimal mode
gold		shift
H.MS+		h.ms addition
H.MS-		h.ms subtraction
H.MS->		convert to decimal hours
L.R.		compute linear regression
LAST x		LAST X
LIST:REG	print the registers
LIST:STACK	print the stack
LIST:\GS	print the statistics registers
LN		natural logarithm
LOG		common logarithm
N!		factorial
P->R		convert polar to rectangular
PRINT x		print the X register
R->P		convert rectangular to polar
RCL 0-9,.0-.5	recall from register
Rv		roll the stack down
R^		roll the stack up
s		compute standard deviation
SCI 0-9		scientific notation mode
SIN		sine
SIN-1		arc sine
STO +,-,x,\:- 0-9	storage arithmetic
STO 0-9,.0-.5		store in register
TAN		tangent
TAN-1		arc tangent
x		multiplication
x-		compute average
x<>y		exchange x and y
x^2		square
y^		linear estimate, correlation
y^x		power
\:-		division
\GD%		percent change
\GS+		add to statistics
\GS-		subtract from statistics
\pi		constant, value 3.141592654
\v/x		square root

Menus::

none

Bugs/ROM-Versions::

none

Notes::

Seven keystroke typeahead buffer.  Page 201 of the manual has a nifty
exploded-view drawing of the calculator.  Page 73 of the manual has a
nifty formula (see "problems").