hp55a

Model:	-55A

General:
	Name:			none
	Code-Name:		Merlin (duplicates -75D name)
	Family:			Classic
	Logic:			RPN
	Features:		scientific, programmable
	Firsts:			timer
	Introduction:
		Date:		1975-1-1
		Price:		$395
	Discontinuation:
		Date:		1977-01-03
		Price:		$335 (price change 1975-10-01)
	Production-Run:		?

Display:
	Type:			LED, 7 segment
	Size:			1 line x 15 chars
	Number-Formats:		sign, 10 mantissa, ., exp sign, 2 exp
	Annunciators:		...............	battery low
				(true decimal has digit to itself)

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-.9
	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:	20
	Program-Steps:		50
	Program-Editing:	replace
	Program-Display:	keycode
	User-RAM-Bytes:		224
	Total-RAM-Bytes:	?
	ROM-Bytes:		?
	Machine-State:		prefix key state
				stack lift enable
				display mode
				degrees / radians / grads
				registers
				program counter
				memory
	File-Types:		none

Physical:
	Technology-Used:	?
	Processor:		?
	Chip-Count:		?
	Power-Source:		3 nickel-cadmium AA cells, AC
	Continuous-Memory:	none
	Expansion-Ports:	none
	I/O-Ports:		none
	Clock:			timer

	Length:			5.8 in
	Width:			3.2 in
	Height:			0.7 to 1.3 in
	Weight:			9 oz
	Temperature-Range:
		Operating:	0 to 50 deg C
		Charging:	10 to 40 deg C
		Storage:	-40 to 55 deg C

Keyboard:
	Switches:		OFF / ON
				TIMER / PRGM / RUN
	Shift-Keys:		f, gold, above left
				g, blue, above right
	User-Defined-Keys:	none

Key-Arrangement::

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

Key-Labels-Base-Keyboard::

	 x
\GS+	y	1/x	%	BST
y^	x<>y	Rv	FIX	SST
f	g	STO	RCL	GTO
ENTER^	CHS	EEX	CLx
-	7	8	9
+	4	5	6
x	1	2	3
\:-	0	.	R/S

Key-Labels-f-gold-above-left::

\GS-	sin	cos	tan	[]
L.R.	ln	log	SCI	[]
[]	[]	x-	LAST x	x\<=y
H.MS+	\v/x	n!	CLR
DEG	in->	ft->	gal->
RAD	lbm->	lbf->	\^oF->
GRD	H->	D->	Btu->
[]	R->	\pi	[]

Key-Labels-g-blue-above-right::

[]	sin-1	cos-1	tan-1	[]
	 x	  x
[]	e	10	[]	[]
[]	[]	s	[]	x=y
	 2
H.MS-	x	[]	CL.R
[]	<-mm	<-m	<-l
[]	<-kg	<-N	<-\^oC
[]	<-H.MS	<-R	<-J
[]	<-P	[]	[]

Programmable-Operations::

%		percent of
+		addition
-		subtraction
0-9, .		enter digit or decimal point
1/x		reciprocal
10^x		common exponentiation
<-H.MS		convert to decimal hours
<-J		convert to BTU
<-kg		convert to pounds of mass
<-l		convert to gallons
<-m		convert to feet
<-mm		convert to inches
<-N		convert to pounds of force
<-P		convert to rectanglular
<-R		convert radians to degrees
<-\^oC		convert to degrees F
Btu->		convert to Joules
CHS		change sign
CL.R		clear .0-.9 and the stack
CLR		clear 0-9 and the stack
CLx		clear X
cos		cosine
cos-1		arc cosine
D->		convert degrees to radians
DEG		set degrees mode
EEX		enter exponent
ENTER^		enter
e^x		natural exponentiation
FIX 0-9		set FIX mode
ft->		convert to meters
gal->		convert to liters
GRD		set grads mode
GTO 00-50	go to line number
H->		convert to hours,minutes,seconds
H.MS+		hours,minutes,seconds addition
H.MS-		hours,minutes,seconds subtraction
in->		convert to millimeters
L.R.		compute linear regression
LAST x		recall last X
lbf->		convert to Newtons
lbm->		convert to kilograms
ln		natural logarithm
log		common logarithm
n!		factorial
R->		convert to polar
R/S		run / stop
RAD		set radians mode
RCL 0-9,.0-.9	recall from a register
Rv		roll the stack down
s		compute standard deviation
SCI 0-9		set SCI mode
sin		sine
sin-1		arc sine
STO +,-,x,\:- 0-9	storage arithmetic (note all registers)
STO 0-9,.0-.9	store into a register
tan		tangent
tan-1		arc tangent
x		multiplication
x-		compute mean
x<>y		swap
x=y 00-50	comparison test, implied go to line number if true
x\<=y 00-50	comparison test, implied go to line number if true
x^2		square
y^		estimate y
y^x		power
\:-		division
\GS+		add to statistics
\GS-		subtract from statistics
\pi		constant, value 3.141592654
\v/x		square root
\^oF->		convert to degrees C

Non-Programmable-Operations::

BST		back step, also clear prefix
f		f-shift
g		g-shift
SST		single step

Timer Mode:

0-9		stores current time in register (splits)
EEX		toggle 1/100 sec display
R/S		start / stop timer

Menus::

none

Bugs/ROM-Versions::

none

Notes::

Shift keys are not merged in programs.

Storage arithmetic does R op X and not X op R.