Texas Instruments TI-57 LCD

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"×1" Display size: 8+2 digits
Weight: 4 oz    
    Entry method: Algebraic with precedence 
Batteries: 2×"LR44" button cell Advanced functions: Trig Exp Cmem 
External power:   Memory functions: +/-/×/÷ 
    Programming model: Fully-merged keystroke entry 
Precision: 11 digits Program functions: Jump Cond Subr Lbl  
Memories: 7(1) numbers Program display: Keycode display  
Program memory: 48 program steps Program editing: Auto-insert program entry  
Chipset:   Forensic result: 9.114640577  

ti57lcd.jpg (27631 bytes)The TI-57 LCD is another example of an inexplicable trend at Texas Instruments in the early 1980s to produce new calculator models that are less functional than their predecessors.

The TI-57 was a good calculator, but it had limited program and memory capacity. So what do the engineers of Texas Instruments do? They create a successor with even less memory! Whereas the TI-57 had 50 program steps and 8 memory registers, the TI-57 LCD has only 49 program steps or 7 memory registers; each memory register "steals" 7 steps of program memory, when the calculator's memory is repartitioned. This severely limits the utility of this machine.

My first TI-57 LCD was, sadly, a sick puppy. Although it looked pristine, it was not functional. Most of the time, its display showed complete gibberish; sometimes I could wreak something apparently sensible out of it, like the word CALC shown on the right here. Since then, fortunately, I was able to obtain some functional copies of this machine, including machines with an alternate paintjob.

Given this machine's limited memory, some otherwise simple algorithms are difficult to implement on it. My favorite example, the Gamma function, is no exception. On implementation that goes easy on the programming steps actually computes the incomplete Gamma function. Technically, elegant, this algorithm is nevertheless a pain in the butt to use: the TI-57 LCD is a very slow machine!

 61.01     00   STO 1
 45        01   yx
 51        02   x-t
 61.00     03   STO 0
 55        04   ÷
 71.00     05   RCL 0
 55        06   ÷
 71.01     07   RCL 1
-32        08   INV lnx
 95        09   =
 61.02     10   STO 2
 51        11   x-t
 23.01     12   LBL 1
 71.01     13   RCL 1
 61.65.02  14   STO× 2
 01        15   1
 61.85.00  16   STO+ 0
 71.00     17   RCL 0
 61.55.02  18   STO÷ 2
 71.02     19   RCL 2
 85        20   +
 51        21   x-t
 65        22   ×
 51        23   x-t
 01        24   1
 95        25   =
 51        26   x-t
-26        27   INV x=t
 22.01     28   GTO 1
 13        29   R/S
 21        30   RST