Texas Instruments TI-56

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:   Display type: Numeric display  
New price:   Display color: Black  
    Display technology: Liquid crystal display 
Size: 6"×3"×½" Display size: 8+2 digits
Weight: 4 oz    
    Entry method: Algebraic with precedence 
Batteries: 2×"LR44" button cell Advanced functions: Trig Exp Hyp Lreg Intg Cmem Units 
External power:   Memory functions: +/-/×/÷/^ 
I/O:      
    Programming model: Partially merged keystroke 
Precision: 11 digits Program functions:  
Memories: 8(1) numbers Program display: Keycode display  
Program memory: 56 program steps Program editing: Overwrite capability  
Chipset:   Forensic result: 9.114640577  

ti56.jpg (28282 bytes)The model number is legendary: the first '56 from Texas Instruments was the venerable SR-56, a superb first-generation programmable calculator. Alas, the TI-56 is a much simpler device: it is programmable only just barely, with a limited amount of program memory and no branching capability. The TI-56, after all, is just the good old TI-55-III, released under yet another model number.

As a programming example, here is a simple program that implements Stirling's formula that approximates the extended factorial:

00  61    STO
01  00    0
02  65    ×
03  02    2
04  65    ×
05  91    π
06  95    =
07  13    √
08  65    ×
09  71    RCL
10  00    0
11  45    yx
12  71    RCL
13  00    0
14  55    ÷
15  71    RCL
16  00    0
17  41    INV
18  44    lnx
19  65    ×
20  53    (
21  71    RCL
22  00    0
23  17    1/x
24  55    ÷
25  01    1
26  02    2
27  85    +
28  01    1
29  95    =
30  22    RST