TI BASIC: Язык программирования калькуляторов Texas Instruments

Programming language used in Texas Instruments calculators
the calculator programming language

TI BASIC is the official name of a BASIC like language built into Texas Instruments (TI)'s graphing calculators. TI BASIC is a language family of three different and incompatible versions, released on different products:
TI BASIC 83 (on Z80 processor) for TI 83 series, TI 84 Plus series
TI BASIC 89 (on 68k processor) for TI 89 series, TI 92 series, Voyage 200
TI BASIC Nspire (on ARM processor) for TI Nspire and TI Nspire CAS
TI rarely refers to the language by name, but the name TI BASIC has been used in some developer documentation. For many applications, it is the most convenient way to program any TI calculator, since the capability to write programs in TI BASIC is built in. Assembly language (often referred to as "asm") can also be used, and C compilers exist for translation into assembly: TIGCC for Motorola 68000 (68k) based calculators, and SDCC for Zilog Z80 based calculators. However, both of them are cross compilers, not allowing on calculator programming. TI BASIC is considerably slower than the assembly language (because it has to be interpreted), making it better suited to writing programs to quickly solve math problems or perform repetitive tasks, rather than programming games or graphics intensive applications. Some math instruction books even provide programs in TI BASIC (usually for the widespread variant used by the TI 82/83/84 series). Although it is somewhat minimalist compared to programming languages used on computers, TI BASIC is nonetheless an important factor in the programming community. Because TI graphing calculators are required for advanced mathematics classes in many high schools and universities, TI BASIC often provides the first glimpse many students have into the world of programming.

The syntax of all versions of TI BASIC are somewhat different from typical BASIC implementations. The language itself has some basic structured programming capabilities, but makes limited to no use of or allowance for white space or indentation. It is also dependent on a somewhat non standard character set, with specific characters for assignment (the right "STO" arrow, not readily available in most character sets), square and cube roots, and other mathematical symbols, as well as tokenized entry and storage for keywords. All statements begin with a colon, which also functions as a statement separator within lines. On the TI 83/84 models, closing parentheses, brackets, braces, and quotes can optionally be omitted at the end of a line or before the STO token in order to save space, although sometimes they are better left on. For example, on TI 83/84 models the for loop function runs much slower without closing parentheses in certain circumstances. Expressions use infix notation, with standard operator precedence. Many statements demand arguments in parentheses, similar to the syntax used for mathematical functions. The syntax for assignment (copying of data into a variable) is unusual with respect to most conventional programming languages for computers; rather than using a BASIC like let statement with an equal sign, or an algol like := operator, TI BASIC uses a right arrow sto→ operator with the syntax: source → destination. This is similar to several Japanese calculators, such as from Casio, Canon and Sharp, that have often employed a similar syntax, ever since the first mass market Japanese alphanumerical calculators appeared in the late 1970s and early 1980s.

TI BASIC is a strongly and dynamically typed language. Available data types differ considerably between the 68k and Z80 versions. It is not possible to create user defined data types without using a library written in assembly. Lists are often used as a replacement for structs.

Flexibility in the use of variables varies widely by the calculator model. For example, on the TI 84 Plus, all English language letters as well as theta (Θ) are available.

On the TI 83/84, the programmer can create lists whose names are up to five characters. All other data types are limited, such as the 27 real or complex variables, and a number of predefined variable names of other types (e. g., matrices have to be one of the ten variables [A] [J]). On the TI 83/84 certain variables such as Ans and the finance variables have fixed addresses in RAM, making them much faster to access than the 27 letter variables. Ans acts as a special variable containing the result of the last evaluated code. A line with just a variable will still be evaluated and its contents stored in Ans as a result. Because Ans is reevaluated so frequently it most often is used to store very temporary calculations or to hold values that would otherwise be slow to access such as items from a list. All variables are global.

In contrast, 68k calculators allow all variable names to have up to eight alphanumeric characters, including Greek. Furthermore, variables can be grouped into "folders", or made local to a program by declaring them with the Local statement.

Z80 programmers often start lines with " (double quotation mark) to denote a comment. Lines starting with " are actually executed changing the Ans variable, but this does not affect anything other than performance unless Ans is read immediately afterwards.

The 68k calculators allow programs to include single line comments, using © as a comment symbol. If a comment appears as the first line after the "Prgm" statement, it is displayed in the status bar when the program is selected in the catalog; such comments are often used to document the names or types of parameters. The 68k interpreter has a built in feature to store the number of space characters at the beginning of a line, this allows indentation.

The Z80 version of TI BASIC makes explicit "functions" like those in 68k impossible. However, all variables are global so functions can be emulated by setting variables, similar to arguments, before calling another program. Return values do not exist; the Return statement stops the current program and continues where the program was called.

The 68k version of TI BASIC allows creating user defined functions. Functions have the same syntax as programs except that they use the Func EndFunc keywords instead of Prgm EndPrgm, and that they are not allowed to use instructions that perform I/O, modify non local variables, nor call programs. However, functions can still be non pure because they can call built in functions such as getTime , getKey , or rand All functions have a return value, which in the absence of an explicit Return statement is the last expression evaluated.

Third party applications, in chronological order Omnicalc, xLIB, Celtic, and Doors CS, have overloaded TI BASIC functions on the Z80 calculators to provide additional language functionality. The third party libraries overload the sum , real , det and identity functions, which are handled and interpreted by their respective applications. Among the extra functions are fast shape drawing routines, sprite and tilemap tools, program and VAT modification and access abilities, GUI construction features, and much more, most of which are ordinarily restricted to use by assembly programmers. All of the functions require that an application like Doors CS 7.0 be present on the user's calculator, sometimes considered a detraction to the use of the libraries.

The following programs, when executed, will display the phrase "HELLO, WORLD! ".