hp35a

Model:	-35A

General:
	Name:			Scientific Pocket Calculator
	Code-Name:		none (Classic?)
	Family:			Classic
	Logic:			RPN
	Features:		scientific
	Firsts:			one at all (also: Classic, RPN, etc.)
	Introduction:
		Date:		1972-07-01 (from wall of fame,
				possibly 1972-02-01)
		Price:		$395
	Discontinuation:
		Date:		1975-02-01
		Price:		$195
	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, S
	Flags:			none
	Register-Usage:		Z is duplicated into T after trig functions
	Numbered-Registers:	none
	Program-Steps:		none
	Program-Editing:	none
	Program-Display:	none
	User-RAM-Bytes:		35
	Total-RAM-Bytes:	49
	ROM-Bytes:		768 (10-bit words)
	Machine-State:		prefix key state
				stack lift enable
				registers
				total of 7, 7-byte registers and 12 status bits
	File-Types:		none

Physical:
	Technology-Used:	?
	Processor:		?
	Chip-Count:		8
				1820-0853 anode driver and system clock
				1820-0854 cathode driers
				1820-0855 clock driver
				1820-0849 CPU control and keyboard scanner
				1820-0848 CPU data
				1818-0024 ROM (256 x 10), 10-pin can
				1818-0026 ROM (256 x 10), 10-pin can
				1818-0028 ROM (256 x 10), 10-pin can
	Power-Source:		3 nickel-cadmium AA cells, AC
	Continuous-Memory:	none
	Expansion-Ports:	none
	I/O-Ports:		none
	Clock:			none

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

Keyboard:
	Switches:		OFF / ON
	Shift-Keys:		none
	User-Defined-Keys:	none

Key-Arrangement::

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

Key-Labels-Base-Keyboard::

 y			 x
x	log	ln	e	CLR
\v/x	arc	sin	cos	tan
1/x	x<>y	Rv	STO	RCL
ENTER^	CHS	EEX	CLx
-	7	8	9
+	4	5	6
x	1	2	3
\:-	0	.	\pi

Programmable-Operations::

none

Non-Programmable-Operations::

+		addition
-		subtraction
0-9, .		enter digit or decimal point
1/x		reciprocal
ARC COS		arc cosine
ARC SIN		arc sine
ARC TAN		arc tangent
CHS		change sign
CLx		clear X
COS		cosine
EEX		start an exponent, 1 not required
ENTER^		enter
e^x		natural exponentiation
ln		natural logarithm
log		common logarithm
RCL		recall from register
Rv		roll the stack down
SIN		sine
STO		store in register
TAN		tangent
x		multiplication
x<>y		exchange x and y
x^y		power
\:-		division
\pi		constant, value 3.141592654
\v/x		square root

Menus::

none

Bugs/ROM-Versions::

On early models, if you did:

	2.02
	ln
	e^x

you got 2.  More fully, we have the text of an official
Hewlett-Packard errata sheet:

	HP-35 Errata

	Exponential Functions

	1. This siutation involves the use of certain
	   numbers, which, when used as the value of
	   "x" in e^x, cause that function to give an-
	   swers that are off by a maximum of one
	   percent.

	   The numbers are 0.,7030975114 and
	   0.995033085 x 10^-2, or integer multiples
	   of the latter number though nine, by itself,
	   or when added to the former.  These num-
	   bers are correct when used by themselves
	   or derived as answers to expressions such
	   as ln 2.02 (ln 2.02 = 0.7030975114).  The
	   idiosyncrasy is in the e^x function, not the
	   logarithmic function.

	   Additionally, since x^y = e^yln x, when yln x
	   equals one of the numbers above, then x^y
	   will also be off slightly less than one percent.

	   To achieve a very good approximation of
	   the proper operation with these numbers,
	   you can simply leave off the last digit of
	   the number to be used as "x" in e^x or x^y.

	2. In e^x, when x = (-2291.072168 +/- 11.512924)
	   x 10^J (J can equal 0 through 96), the HP-35
	   will indicate overflow (9.999999999 x 10^99)
	   when it should indicate underflow (0).  The
	   numbers mentioned above are beyond the
	   dynamic range of the calculator.


	Trigonometric functions

	1. The HP-35 gives the following answers:

		arc sine 0.0002 = 5.729577893 x 10^-3
		arc cosine 0.0002 = 89.99427042
		arc tangent 0.0002 = 5.729577893 x 10^-3

	The correct answers are:

		arc sine 0.0002 = 0.01145916
		arc cosine 0.0002 = 89.98854
		arc tangent 0.0002 = 0.1145916

	2. The HP-35 gives the arc tangent of
	   1.00020002 as 45; the correct answer is
	   45.00573.  This represents an error of ap-
	   proximately one one-hundredth of one
	   percent.

	3. There is a deviation of approximately one
	   one-hundredth of a percent in the arc sine
	   and are cosine of these numbers (arc
	   tangent is correct):

		0.7071774882		0.7071774884
		0.7071774883		0.7071774885

	The HP-35 gives 45 for the arc sine and co-
	sine of these numbers; the arc sine should be
	approximately 45.005730, and the arc cosine
	should be approximately 44.994270.

	We are confident that this list represents the
	range of errors in the calculator.

		Hewlett  hp  Packard

		Advanced Products
	10900 Wolfe Road, Cupertineo, CA 95014

Try:

	0
	CHS
	\v/

and you will get an error, even though it can take the square root of zero.

These bugs _may_ have caused a recall.  Rumor.  Not confirmed.

Notes::

"Original" non-programmable hand held slide rule.  Had x^y not y^x!

Price went down to $295 when the -45A was introduced.

The trig functions compute in degrees only.

The ROM was on three chips.  All are active and read the same (8-bit)
address.  Only one is selected, and only that chip's data is returned.

price changes:

	1973-05-01	$295
	1974-05-01	$225
	1975-02-01	$195

Early units had a small hole to the right of the ON/OFF switch.  This
hole had an "on" light, which is of course redundant.

Very early units just had "Hewlett-Packard" with no model number.

Early models had labels printed above the key, not molded into the keys.

The story is that it was called the 35 because it had 35 keys.  The
logic behind other calculator numbers is, shall we say?, less obvious.

There is a rumor that 1 or 2 units were custom built with green LEDs
for either Carl Hewlett or Dave Packard.  The green LEDs drew much
more power.

------------------------------------------------------------
letter from Jordi Hidalgo in DATAFILE V22 N1 p4, January/February 2003

Quoted from HP-35 Math Pac manual, page 168:

How would you display all 1's, 2's, ... 9's?

1's: 9 e^x e^x 9     EEX 88 \:-
2's: 9 e^x e^x 4.5   EEX 77 \:-
3's: 9 e^x e^x 3     EEX 66 \:-
4's: 9 e^x e^x 2.25  EEX 55 \:-
5's: 9 e^x e^x 1.8   EEX 44 \:-
6's: 9 e^x e^x 1.5   EEX 33 \:-
7's: 7.777777777 EEX 7
8's: 9 e^x e^x 1.125 EEX 11 \:-
9's: 9 e^x e^x

The author found a shorter way to do 7:

7's: 9 1/x 7 EEX 78 *

Tony Duell has a nice "HP-35 Internals..." article in DATAFILE V22 N6 P11.