Retro: A Quick Look at the TI-74 Basicalc
Back to the 1980s Again
Recently I
purchased a Texas Instruments TI-74 Basicalc calculator. The calculator came in great condition,
including manuals and a Mathematics module (and the module).
The TI-74 is a
BASIC programming calculator (similar to Hewlett Packard’s HP-71B and HP-75 and
Casio’s fx-795P). The keyboard of the
TI-74 is very busy and has a QWERTY keyboard.
The keys are nice but I am not able to type fast on it. The calculator takes four AAA batteries. The calculator I got was produced in
1985. The original cost was around $130,
which was a pretty good price for a basic portable BASIC computer/calculator at
the time.
 |
| HP 71B (top) and TI-74 (bottom). The 74 is a giant! |
The TI-74 is a
BASIC programming calculator (similar to Hewlett Packard’s HP-71B and HP-75 and
Casio’s fx-795P). The keyboard of the
TI-74 is very busy and has a QWERTY keyboard.
The keys are nice but I am not able to type fast on it. The calculator takes four AAA batteries. The calculator I got was produced in
1985. The original cost was around $110-$130,
which was a pretty good price for a basic portable BASIC computer/calculator at
the time. The one I got on Amazon, originally sold at Brendle's (a defunct chain store which was based in Elkin, North Carolina)
Calculator Mode vs. BASIC Mode
Modes are
switched back and forth with the [ MODE ]
toggle key.
Calculator Mode
Like the
HP-71B, the TI-74 has two modes: Calculator and BASIC mode. In Calculator mode, the QWERTY keyboard
becomes a scientific calculator, with all the functions stated in blue. For
example, the [ S ] key is the angle change key [ DRG
], while the [ U ] key becomes the square key [ x2
]. In Calculator mode, the TI-74
operates as an AOS (Algebraic Operating System) calculator. If have worked with a TI-30Xa or a classic
TI-36X Solar, you should be familiar with it.
The Display
The numbers are
aligned to the right. What is neat about
the display is that the last function used will also be displayed. For example:
cos(√19°):
|
Keys
|
Screen
|
|
[DRG] (S) to degrees mode
|
DEG is
highlighted
|
|
19
|
19 |
|
|
[ √x ] (I)
|
4.358898944 | √x
|
|
[ cos ] (W)
|
.99710753 | cos
|
Two
Argument Functions
One of the
quirks about the Calculator mode is how two argument functions are
operated. For input, you will need to
press [ (x,y) ] (the L key).
Combinations
and Permutations: Enter n, press [ (x,y) ] (L), r and press either [ nCr ] (J) for combinations or [ nPr ] (H) for permutations.
Polar to
Rectangular: Enter r, press [ (x,y) ] (L), then θ, [ P>R
] (F). x is displayed first,
press [x<>y] (RUN) to show y.
Rectangular to
Polar: Enter x, press [ (x,y) ] (L), then y, press [ INV
] (SHIFT), [ P>R ] (F). r is displayed first, press [x<>y] (RUN) to show θ.
Strangely
enough, this isn’t the percent change function works. Enter the new amount, press [Δ%] (SPACE), then the old amount. For example, if I wanted to find the percent
change from 150 to 180, I would key in 180, [Δ%],
150, [ = ] to get 20. (20% increase)
This is also the same way of how to computer percent changes with the
TI-55 III.
Statistics: Only Available
in Calculator Mode
The statistics
module of the TI-74’s calculator mode can handle either one-variable date or
linear regression (y = a + bx). You call
statistical variables and clear its registers by first pressing the [ STAT ] (CTL)
key. All the statistical variables are
marked in yellow.
BASIC Mode
By default, the
TI-74 has 7,710 bytes of memory. You can
add a memory module that would affectively double the memory. This is also where you can access any ROM
module commands.
The language of
the TI-74 is straight forward. What is
neat is that the case that comes with the TI-74 has syntax of the BASIC
commands available card for reference.
There is only
one program space (similar to early keystroke calculators like TI-58C and
HP-12) on which all the programming steps are shared, with no separate file management. However, you are able to run the program
space from any designated line number, so you can fit multiple routines on the
TI-74. You can designate the line
numbers from 1 to 32766, and each line numbers can become multi-statement lines
with the use of colons. (:)
Over the course of the next month or so, I
hope to post programs for the TI-74.
Here is one that I did as my first TI-74 routine (sum of f(x)):
100 INPUT “lower:”;L
105 INPUT “upper:”;U
110 T=0
115 FOR X=L TO U
120 GOSUB 150
125 T=T+F
130 NEXT X
135 PRINT “total=”;T:PAUSE
140 END
150 F=X^2 \\ or any f(X)
155 RETURN
Make sure all
the routines have END, that stops execution.
The default case for the alpha keys in BASIC mode is lower case. To get the upper case lock, press [SHIFT]
[UCL].
The only thing
I am not crazy about is that the BASIC functions are printed in gray and it can
be hard to see when holding the TI-74 at different angles.
Mathematics Module
The Mathematics
Module for the TI-74 is very sophisticated.
I haven’t had much time to play with the module, but the module provides
the following functions:
* Complex
functions (COMPF): Arithmetic, Logarithms, Powers, Trigonometric, Parts of the Rectangular
and Polar forms. This is really full-fledged,
especially for complex numbers in the 1980s.
* Gamma
Function (GAM)
* Polynomial
Multiplication (POL): This program
calculates the coefficients of p(x) * q(x)
* Curve
Analysis: Cubic Splines, Relative Minimum, Root Finder by either Bisection or
Newton’s Method
*
Calculus: Convolution, Runge-Kutta
(differential equations), Gauss Quadrature (integrals)
* Matrices: 3 x
3 systems including complex numbers, Matrices Utilities (addition, multiplication,
inverse, simultaneous equation, determinant), Tridiagonal Solving routine
Peripherals
The TI-74 can
be attached to a compatible printer or a module that allows programs to be
recorded on cassettes.
On a side note… HHC 2016!
I will be going
to the HHC 2016 conference in two weeks (9/17 – 9/18/16) in Fort Collins, CO.
Eddie
This blog is
property of Edward Shore, 2016.