Texas Instruments TI-74

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: 1985  Display type: Alphanumeric display  
New price:   Display color: Black  
    Display technology: Liquid crystal display 
Size: 4½"×8½"×1½" Display size: 31 characters
Weight: 16 oz    
    Entry method: Algebraic with precedence 
Batteries: 4×"AAA" alkaline Advanced functions: Trig Exp Hyp Lreg Cmem 
External power:   Memory functions:  
I/O: I/O port, expansion port     
    Programming model: BASIC 
Precision: 14 digits Program functions: Jump Cond Subr Lbl Ind  
Memories: 8(0) kilobytes Program display: Text display  
Program memory: 8 kilobytes Program editing: Text editor  
Chipset:   Forensic result:  

*Peripherals include the PC-324 printer and the CI-7 cassette interface cable.

ti74.jpg (36341 bytes)The Texas Instruments TI-74 is a close relative to TI's earlier BASIC language programmable calculator, the Compact Computer-40. It is a quite capable handheld computer with an innovative feature: in "calculator mode", it operated like a conventional algebraic calculator with postfix and infix operators. (That is, in this mode, you'd type 5 + 3 = to obtain a result of 8, or 30 sin to obtain the result of 0.5.) This mode even offers ten numbered registers! This calculator mode addresses many of the shortcomings (well, I think they're shortcomings) that are a result of using a programming language like BASIC as the primary language interface of a handheld device.

The TI-74 has a peripheral port through which dedicated peripherals, such as a printer or cassette recorder interface, can be attached.

The TI-74 has an interesting variant: an OEM version called the TI-74S. Until I got my hands on one by accident (I thought I was buying a TI-74) I didn't know such a model even existed! This, obviously, is a customizable version of the TI-74 (the "Custom Program" label on the plastic shell case is a dead giveaway.) One characteristic of this version is that, just like on the "blanknut" versions of the HP-41, many of the keyboard labels are missing.

The similarity with the CC-40 is demonstrated by the fact that an identical implementation of the Gamma function works on both machines. Here is this example program again, for reference:

100 DATA 76.18009172947
110 DATA -86.50532032942
120 DATA 24.01409824083
130 DATA -1.23173957245
140 DATA 1.208650973866e-3
150 DATA -5.395239384953e-6
160 INPUT "X=? ";X
170 T=1
180 IF X>=0 THEN GOTO 220
190 T=T*X
200 X=X+1
210 GOTO 180
220 G=1.00000000019
230 FOR I=1 TO 6
240 READ P
250 G=G+P/(X+I)
260 NEXT
270 G=LN(SQR(2*PI)*G/X)
280 G=G-X-5.5+LN(X+5.5)*(X+.5)
290 PRINT "G(X)=";EXP(G)/T