true

'''TI-83 BASIC''' is not affiliated with BASIC .

'''TI-83 BASIC''' or TI-BASIC 83 is the high-level language used on TI-83/84/83+/84+ Z80 calculators (aside from the assembly which is also on the calculator).

Elements of language

Control flow

The language contains control flow for structured programming. The main control flow statements are:

=If=

If condition
Then
...
Else
...
End

=For=

For(variable,start,stop,step)
...
End

=While=

While condition
...
End

=Repeat=

Repeat condition
...
End

Data types

'''TI-BASIC''' is a strongly and dynamically-typed language Variables are global. There is no local variables. So programs cannot be recursive, even if a program can call itself.

'''Numerical variables''', 27 variables from A to Z and theta. These allow real numbers or complex numbers (implemented as pairs of reals) to be stored in floating point format. Values may range from 1E-99 to 1E99 with up to ten digits of accuracy.
'''Strings''', 10 strings from Str1 to Str9 and Str0.
'''Lists''', including L1 - L6, with the ability to create additional ones. These are essentially one-dimensional arrays used to store a real or complex number into each of their elements. (L1(4) would return the value of L1 at n=4)
'''Matrices''', 8 matrices from [A] to [J]. Their elements are subject to the same restrictions as lists. Their dimensions may be defined up to 99x99 elements, although, again, available memory will limit this. (A would design item at row=3 column=4)
'''Equation variables''', 10 y(x) functions: from Y1 to Y9 and Y0, 6 r(theta) polar functions: r1 - r6, and 3 u(n) integer sequences: u, v, w. (Y1(4) would return the value of Y1 at X=4, X is a real)

Example

One popular example is the quadratic formula program.

Prompt A,B,C
B²-4AC->D
(-B-sqrt(D))/(2A)->Y
(-B+sqrt(D))/(2A)->X
{Y,X}

As far there is a complex mode and variable can be real or complex, this program is very ubiquitous.

Merged content

This implementation (in TI-83 BASIC) has quite a few limitations. Among them:

TI-BASIC doesn't have any concept of ASCII, so the . command, which is translated to Disp , outputs everything on a new line as a number. Input is taken whenever a comma is encountered as opposed to being presupplied, and again takes numbers as input. [Attempting to input a string (enclosed in "quotes") will, because of a weird glitch in the interpreter, work without throwing an error: it stores the string to a custom list (yes, a list) named 'V', not the variable V (which remains unaffected). Attempting to access this list throws an ERR:DATA TYPE.]
In order to simplify the main loop, all commands are stored to list L1 at the beginning. Lists (arrays) in TI-BASIC can't be more than 999 elements, so attempting to run a program exceeding that size will throw an error (probably INVALID DIM). This can be fixed at the cost of speed and size.
Speaking of which: the interpreter is... on the slow side, to put it nicely.

This was made to be compatible with [http://sc.cemetech.net SourceCoder], so the tilde (~) translates to the negative sign (the (-) key) and -> is the arrow on the STO> key.

Input "",Str1 //program input seq(inString("<>-+.,[]",sub(Ans,S,1)),S,1,length(Str1->L2 cumSum((Ans=7)-(Ans=8->L3 seq(Ans(X),X,dim(Ans),1,~1->L4 1->P:DelVar L11->dim(L1 //this is the same as DelVar L1:1->dim(L1 as DelVar doesn't require a colon or newline after its argument For(S,1,dim(L2 L2(S->T P-(T=1)+(T=2->P //< and >, respectively dim(L1 Ans+(P-Ans)(P>Ans->dim(L1 L1(P)-(T=3)+(T=4->L1(P //- and + If T=5 //. Disp L1(P If T=6:Then //, Input V V->L1(P End If T=7 and not(L1(P //[ S+2+sum(not(cumSum(L3(S)-1=seq(L3(X),X,S+1,dim(L3->S If T=8 and L1(P:Then //] 1+dim(L3)-S (Ans+S)-(Ans+sum(not(cumSum(L4(Ans)=seq(L4(X),X,Ans+1,dim(L4->S End End