TI-81
Graphing calculator produced by Texas Instruments
From Wikipedia, the free encyclopedia
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 Since its release, it has been superseded by a series of newer calculators; most of these are functionally similar to the TI-81, with the exception of the TI-Nspire series.
 A 1994 TI-81 showing graphs | |
| Type | Graphing calculator |
|---|---|
| Manufacturer | Texas Instruments |
| Introduced | 1990 |
| Discontinued | 1997[1] |
| Successor | TI-82 |
| Calculator | |
| Entry mode | D.A.L. |
| Precision | 13 digits |
| Display size | 96×64 pixels, 16×8 characters |
| CPU | |
| Processor | Zilog Z80 |
| Frequency | 5 MHz or 6 MHz[2] |
| Programming | |
| Programming language(s) | TI-BASIC, Assembly |
| User memory | 2400 bytes of RAM |
| Other | |
| Power supply | 4 AAAs, 1 CR1616 or CR1620 |
| Weight | 168 grams (5.9 oz) |
| Dimensions | 173 mm × 79 mm × 22 mm (6.8 in × 3.1 in × 0.85 in) |
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.[3]
In late 2009 an exploit was found that can be used to execute machine code on the TI-81, using manual input of code.[4] 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.[5]
Texas Instruments produced an emulator for the TI-81 and its Equation Operating System on a desktop computer; it is compatible with MS-DOS.[6]