TI-81

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title: "TI-81" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["graphing-calculators", "texas-instruments-programmable-calculators", "computer-related-introductions-in-1990", "z80"] description: "Graphing calculator produced by Texas Instruments" topic_path: "general/graphing-calculators" source: "https://en.wikipedia.org/wiki/TI-81" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Graphing calculator produced by Texas Instruments ::

::data[format=table title="Infobox Calculator"]

Field	Value
name	TI-81
image	TI-81_Calculator_on_Graph_Screen.jpg
caption	A 1994 TI-81 showing graphs
type	Graphing calculator
entry	D.A.L.
manufacturer	Texas Instruments
introduced	1990
discontinued	1997
successor	TI-82
processor	Zilog Z80
frequency	5 MHz or 6 MHz
memory_user	2400 bytes of RAM
display_size	96×64 pixels, 16×8 characters
precision	13 digits
prog_lang	TI-BASIC, Assembly
supply	4 AAAs,
1 CR1616 or CR1620
weight	168 g
dimensions	6.8 x
::

|name = TI-81 |image = TI-81_Calculator_on_Graph_Screen.jpg |caption = A 1994 TI-81 showing graphs |type = Graphing calculator | entry =D.A.L. |manufacturer = Texas Instruments |introduced = 1990 |discontinued = 1997 |successor = TI-82 |processor = Zilog Z80 |frequency = 5 MHz or 6 MHz |memory_user = 2400 bytes of RAM |display_size = 96×64 pixels, 16×8 characters |precision = 13 digits |link = |prog_lang = TI-BASIC, Assembly |supply = 4 AAAs, 1 CR1616 or CR1620 | weight = 168 g | dimensions = 6.8 x The TI-81 was the first graphing calculator made by Texas Instruments. It was designed in 1990 for use in algebra and pre-calculus courses. Since its release, it has been superseded by a series of newer calculators; most of these are functionally similar to the TI-81, with the exception of the TI-Nspire series.

Features

The TI-81 is powered by a Zilog Z80 microprocessor, like those used in most other Texas Instruments graphing calculators. However, its processor is clocked at 2 MHz, whereas the others run at a frequency of either 6 or 15 Mhz. It has 2.4 KB of user-accessible RAM, with additional RAM being allocated to the calculator's internal firmware.

The calculator uses Texas Instruments' own in-house operating system, the Equation Operating System; the firmware used by all other Texas Instruments graphing calculators derive from this. The TI-81 can perform two-dimensional parametric graphing—in addition to standard two-dimensional function graphing, trigonometric calculations in units of either degrees or radians, simple drawing, the creation and manipulation of matrices up to a size of 6 by 6 pixels, and the execution of simple programs in a proprietary, statement-based language.

In late 2009 an exploit was found that can be used to execute machine code on the TI-81, using manual input of code. The TI-81 has no data link interface; its only means of input and output are the keyboard and screen.

Like most other Texas Instruments graphing calculators, the TI-81 is powered by four AAA batteries and one button cell backup battery; the backup battery makes sure that programs loaded in memory are persistent during battery changes. Some early TI-81 units omit the backup battery.

Texas Instruments produced an emulator for the TI-81 and its Equation Operating System on a desktop computer; it is compatible with MS-DOS.

References

References

1. Woerner, Joerg. (2009-02-08). "DATAMATH: TI-81 (1995)".
2. "TI-Planet's calculator comparison tool".
3. "TI-81 Guidebook". [[Texas Instruments, Inc.]].
4. (2009-08-17). "User Machine Code Execution on TI-81 Becomes a Reality".
5. (2009-01-27). "DATAMATH: TI-81 Engineering Sample".
6. (1998-04-28). "PC-81 on ticalc.org".

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