
TI80 

TI80 (left), TI84 Plus CE (right) 

Look how thin the TI80 is 
Retro Review: Texas
Instruments TI80
First, thank you Nano for the TI80 (along with giving me a
pair of slide rules and an astronomy poster)!
Much appreciated!
Essentials
Company: Texas Instruments
Years: 1995
Type: Graphing, Programming
Memory: 7,034 bytes
Operating System: Algebraic
Memory Registers:
27 (AZ, θ)
Screen: Monochrome
Batteries: 2 CR2032 batteries
Graphing
Modes: Function (4), Parametric (3). Table included.
Regressions: 6: Linear (ax + b), Quadratic, Linear (a +
bx), Logarithmic, Exponential, Power
Lists: Up to 99
entries per lists, 6 lists available (L1 through L6)
Matrices: none
Complex
Numbers: none
Keyboard
The keyboard is
what one would expect on a Texas Instruments graphing calculator: nice and
responsive.
Screen
The screen is
small. Not kidding. The screen is only 48 x 64 pixels big,
accompanying 8 lines of 16 characters. That
means that the font is small. What is wild
is that the pi symbol (π) does not conform to the rest of the font, and is
twice as long as the rest of the characters.
The screen is still
bigger than the minigraphing calculators such as the Casio fx6300g or the
Hewlett Packard HP9g.
Is the TI80 a simplified TI81?
For the most part,
no. Sure, the TI80 does not have
matrices and hyperbolic functions (sinh, cosh, etc) like the TI81. However, the TI80 has fractions (see the
next section), integer division and remainder function, random integer, a complementary
table mode, and lists. The number of
stat plots increased to 3, which they don’t have to depend on the statistics
mode.
As far as
programming memory, the TI80 beats the TI81: 7,034 bytes to 2,400 bytes. Also, you can go beyond 37 programs for the
TI80, as the names are not restricted to one character.
Fractions
The TI80 has a
dedicated fraction menu, which allow users to convert between improper and
proper form, as well as conversion between fraction and decimal approximation. The Manual Simplification mode allows
fractions to not be automatically simplified on calculation.
To enter fractions,
the format is: A _ B / C
Note that the slash
is bold. Merely pressing the division key
will not register the fraction.
To separate the
whole part from the fraction, press [ 2nd ] [ + ] (UNIT_).
To separate the
numerator from the denominator, press [ 2nd ] [ ÷ ] (b/c).
Example: Enter 2 3/4
Keystrokes: 2 [ 2nd ] [ + ] 3 [ 2nd ] [ ÷ ] 4
According to
Datamath (
http://www.datamath.org/Graphing/TI80.htm
), the TI80 would get replaced with the TI73 in 1998. This may mean that the TI80 became the base
for the TI73 series (TI73, TI73 explorer).
Lists
The TI80 allows
for 6 lists, each with a 99 element capacity.
Arithmetic can be operated on two samesized lists, on an
elementbyelement functions. Lists
functions include sorting, dimension, minimum, maximum, sum of the elements,
product of the elements, and sequence generation.
Programming
Programming is
fairly basic for the TI81. Commands:
IfThenElseEnd
Structure (IF, THEN, ELSE, END)
Quick if structure
ForEnd structure
(no IS>, DS< this time) (FOR, END)
Labels: one character and local labels (LBL, GOTO)
Subroutines (PRGM_,
RETURN)
Drawing commands
include points, shading (three types, general, Y<, Y>)
Since the only
builtin calculus function of the TI80 is numerical derivation (NDERIV), two
programs for Newton’s Method and Simpson’s Rule are presented below.
TI80 Program: SOLVEY1 (Newton’s Method)
80 bytes
The equation is
stored in Y1. The program solves for X
in Y1(X) = 0
INPUT “GUESS:”, X
LBL 0
XY1/NDERIV(Y1,X,X)→N
IF ABS (XN)>1E10
THEN
N→X
GOTO 0
END
N→X
DISP “X = “, X
Example: X^23X+1, guess X = 3
Result: X =
2.618033989
TI80 Program: SIMPY1
(Integral, Simpson’s Rule)
140 bytes
The equation is
stored in Y1. The program calculates ∫(Y1,X,A,B)
RADIAN
INPUT “A:”,A
INPUT “B:”,B
INPUT “N (EVEN):”,N
(BA)/N→H
0→T
FOR(I,1,N1)
A+IH→X
T+2*Y1→T
IF FPART(I/2)≠0
2*Y1+T→T
END
(T+Y1(A)+Y1(B))H/3→T
DISP “INTEGRAL:”,T
Example: X^23X+1, with A = 0 to B = 5 and N = 10
Result: X = 9.166666667
Final Verdict
The TI80 is a nice introductory calculator, and thanks to
programming a lot can be done with it. I
wish the screen was bigger and degree/degreesminutesseconds conversions were
available, but other than that, it was a great calculator which provides a lot
of features (maybe not as intimidating as more advanced calculators).
It is a nice calculator to add to the collection, and I thank you Nano
immensely.
Eddie
This blog is property of Edward Shore, 2017.