The TI-81 is the first graphing calculator

Graphing calculator

A graphing calculator typically refers to a class of handheld calculators that are capable of plotting graphs, solving simultaneous equations, and performing numerous other tasks with variables...

 made by Texas Instruments

Texas Instruments

Texas Instruments Inc. , widely known as TI, is an American company based in Dallas, Texas, United States, which develops and commercializes semiconductor and computer technology...

. It was designed in 1990 for use in algebra

Algebra

Algebra is the branch of mathematics concerning the study of the rules of operations and relations, and the constructions and concepts arising from them, including terms, polynomials, equations and algebraic structures...

 and precalculus

Precalculus

In American mathematics education, precalculus , an advanced form of secondary school algebra, is a foundational mathematical discipline. It is also called Introduction to Analysis. In many schools, precalculus is actually two separate courses: Algebra and Trigonometry...

 courses. Since its original release, it has been superseded several times by newer calculators - the TI-82

TI-82

The TI-82 is a graphing calculator made by Texas Instruments. The TI-82 was designed in 1993 as a stripped down, more user friendly version of the TI-85, and as a replacement for the TI-81. It was the direct predecessor of the TI-83. It shares with the TI-85 a 6 MHz Zilog Z80 microprocessor...

, the TI-83, the TI-83 Plus, TI-83 Plus Silver Edition, the TI-84 Plus, the TI-84 Plus Silver Edition, and most recently the TI-Nspire and TI-Nspire CAS

TI-Nspire CAS

The TI-Nspire product line is a series of graphing calculators developed by Texas Instruments. This line currently includes the TI-Nspire, TI-Nspire CAS, TI-Nspire CX and TI-Nspire CX CAS. There is also software available for Windows and Mac OS X that act in simlar ways to the calculators and allow...

; most of these share the original feature set and 96×64-pixel

Pixel

In digital imaging, a pixel, or pel, is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled....

 display that began with this calculator.

Features

The TI-81 is powered by a Zilog Z80

Zilog Z80

The Zilog Z80 is an 8-bit microprocessor designed by Zilog and sold from July 1976 onwards. It was widely used both in desktop and embedded computer designs as well as for military purposes...

 microprocessor

Microprocessor

A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...

, like those used in almost every other Texas Instruments graphing calculator (except the TI-80

TI-80

TI-80 is a graphing calculator made by Texas Instruments. It was originally designed in 1995 to be used at a middle school level .The TI-80 featured the smallest screen and slowest processor of any TI graphing calculator. In comparison, the TI-81, released in 1990, featured a 2 MHz Zilog Z80...

, TI-89, TI-89 Titanium, TI-92, TI-92 Plus, Voyage 200 and TI-Nspire series). However, the processor runs at only 2 MHz whereas the other Z80-powered Texas Instruments calculators run at a speed of at least 6 MHz (the TI-83 Plus Silver Edition, TI-84 Plus, and TI-84 Plus Silver Edition run at 15 MHz). It contained 2.4 KB

Kilobyte

The kilobyte is a multiple of the unit byte for digital information. Although the prefix kilo- means 1000, the term kilobyte and symbol KB have historically been used to refer to either 1024 bytes or 1000 bytes, dependent upon context, in the fields of computer science and information...

 of RAM.

The TI-81's user interactions are provided by its so-called Equation Operation System. This is comparable to the interface provided by the more recent TI-82, TI-83, and so on. This system is capable of such tasks as two-dimensional parametric graphing (in addition to standard two-dimensional function graphing), trigonometric calculations in units of either degrees or radians, simple drawing capabilities, creation and manipulation of matrices up to 6x6 in size, and programming in Texas Instruments' native TI-BASIC

TI-BASIC

TI-BASIC is the unofficial name of a BASIC-like language built into Texas Instruments 's graphing calculators, including the TI-83 series, TI-84 Plus series, TI-89 series, TI-92 series , TI-73, and TI-Nspire...

 programming language.

In early 2010, an exploit was found that can be used to execute machine code on the TI-81, using manual input of code instead of sending programs using a link cable.

As with its successors, the TI-81 is powered by four AAA batteries

AAA battery

A triple A or AAA battery is a standard size of dry cell battery commonly used in portable electronic devices. A carbon-zinc battery in this size is designated by IEC as "R03", by ANSI C18.1 as "24", by old JIS standard as "UM 4", and by other manufacturer and national standard designations that...

 and one CR1616 or CR1620 lithium

Lithium battery

Lithium batteries are disposable batteries that have lithium metal or lithium compounds as an anode. Depending on the design and chemical compounds used, lithium cells can produce voltages from 1.5 V to about 3.7 V, over twice the voltage of an ordinary zinc–carbon battery or alkaline battery...

 backup battery

Battery (electricity)

An electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy. Since the invention of the first battery in 1800 by Alessandro Volta and especially since the technically improved Daniell cell in 1836, batteries have become a common power...

(to ensure programs are kept when the AAA batteries are being changed). Some TI-81 units omit the backup battery; if the AAA batteries of one of these units are changed one at a time and quickly, the memory contents are still retained.

Texas Instruments distributes software which emulates the TI-81 and its Equation Operating System on a desktop computer.

External links

• ticalc.org – The largest archive of TI programs available.