Hewlett-Packard HP-19C

Datasheet legend
Ab/c: Fractions calculation
AC: Alternating current
BaseN: Number base calculations
Card: Magnetic card storage
Cmem: Continuous memory
Cond: Conditional execution
Const: Scientific constants
Cplx: Complex number arithmetic
DC: Direct current
Eqlib: Equation library
Exp: Exponential/logarithmic functions
Fin: Financial functions
Grph: Graphing capability
Hyp: Hyperbolic functions
Ind: Indirect addressing
Intg: Numerical integration
Jump: Unconditional jump (GOTO)
Lbl: Program labels
LCD: Liquid Crystal Display
LED: Light-Emitting Diode
Li-ion: Lithium-ion rechargeable battery
Lreg: Linear regression (2-variable statistics)
mA: Milliamperes of current
Mtrx: Matrix support
NiCd: Nickel-Cadmium rechargeable battery
NiMH: Nickel-metal-hydrite rechargeable battery
Prnt: Printer
RTC: Real-time clock
Sdev: Standard deviation (1-variable statistics)
Solv: Equation solver
Subr: Subroutine call capability
Symb: Symbolic computing
Tape: Magnetic tape storage
Trig: Trigonometric functions
Units: Unit conversions
VAC: Volts AC
VDC: Volts DC
Years of production: 1977-1979 Display type: Numeric display  
New price: USD 345.00   Display color: Red  
    Display technology: Light-emitting diode 
Size: 6½"×3"×1½" Display size: 10(8+2) digits
Weight: 12 oz    
    Entry method: Reverse Polish Notation 
Batteries: 4×"AA" NiCd Advanced functions: Trig Exp Cmem Prnt 
External power: HP adapter   Memory functions: +/-/×/÷ 
I/O:      
    Programming model: Fully-merged keystroke entry 
Precision: 10 digits Program functions: Jump Cond Subr Lbl Ind  
Memories: 30 numbers Program display: Keycode display  
Program memory: 98 program steps Program editing: Auto-insert program entry  
Chipset:   Forensic result:  

hp19c.jpg (27440 bytes)The HP-19C is a printing version of the HP-29C calculator. It was, and still remains, one of the smallest printing programmable calculators ever made. The programming model is essentially identical to that of the HP-29C, except that printer-specific instructions have been added.

A while back, I bought an HP-19C that looked like a hopeless wreck; not only were there parts missing, but the two circuit boards, which are connected by a series of pin connectors, were crushed together, with most connectors bent, some broken. After I unbent the pins and repaired most of the obvious damage, I was quite surprised to find that the calculator was electronically sound, and although its printer looked beyond repair, all calculator functions were working. Then recently, I bought a non-working HP-19C; this one was in much better shape cosmetically, but it appears to have been damaged electronically. But guess what: its printer works! So now, after some transplant surgery, I have a fully functional HP-19C in my hands, and another with broken electronics, a broken printer, a missing printer cover release latch, and a missing battery cover.

The demonstration program below is a standard implementation of the Gamma function, utilizing indirect addressing and the DSZ loop instruction. Before running the program, registers 1-7 must be populated with the constants shown. To use the program, enter the desired argument and hit GSB 0.

M1:    76.18009173
M2:    -86.50532033
M3:    24.01409824
M4:    -1.231739572
M5:    1.208650974e-3
M6:    -5.395239385e-6
M7:    √2π = 2.506628275

01  25 14 00	LBL 0
02  01		1
03  11		x-y
04  25 14 02	LBL 2
05  00		0
06  16 31	x<=y
07  14 01	GTO 1
08  12		Rv
09  21		ENTER
10  12		Rv
11  51		×
12  12		Rv
13  12		Rv
14  12		Rv
15  01		1
16  41		+
17  14 02	GTO 2
18  25 14 01	LBL 1
19  12		Rv
20  45 07	STO 9
21  11		x-y
22  45 08	STO 8
23  06		6
24  45 00	STO 0
25  01		1
26  25 14 03	LBL 3
27  55 12	RCL i
28  55 09	RCL 9
29  55 00	RCL 0
30  41		+
31  61		÷
32  41		+
33  25 45	DSZ
34  14 03	GTO 3
35  55 07	RCL 7
36  51		×
37  55 09	RCL 9
38  61		÷
39  16 32	ln
40  55 09	RCL 9
41  05		5
42  63		.
43  05		5
44  41		+
45  16 32	ln
46  55 09	RCL 9
47  63		.
48  05		5
49  41		+
50  51		×
51  41		+
52  55 09	RCL 9
53  31		-
54  05		5
55  63		.
56  05		5
57  31		-
58  25 32	ex
59  55 08	RCL 8
60  61		÷
61  25 13	RTN