TI-81
The TI-81 was the first graphing calculator produced by Texas Instruments.
| Type | Graphing |
|---|---|
| Manufacturer | Texas Instruments |
| Introduced | 1990 |
| Discontinued | 1995 |
| Latest firmware | V2.0V |
| Successor | TI-85 |
| Calculator | |
| Entry mode | D.A.L. |
| Precision | 13 |
| Display type | Dot-matrix LCD |
| Display size | 96x64 pixels, 16x8 characters |
| Programming | |
| Programming language(s) | TI-BASIC, Z80 assembly |
| User memory | 2400 Bytes |
| Interfaces | |
| Ports | None |
| Other | |
| Power consumption | 4x AAA + CR1620 Batteries |
Features
- Graphing up to 4 equations at a time
Programming
Programming on the TI-81 is far more limited compared to future models. All programs need to be typed in by hand, as there is no external connectivity of any kind.
By default, it only allows writing programs in an early version of TI Basic. The programs are limited in memory consumption, and are all labeled from Prgm0-9, then PrgmA-Z, and Prgmθ. They can also be given a custom label, however. Each program is also limited in line count and total memory consumption.
In 2009, an exploit was found that allows the user to type in machine code directly.[1] A program loader called Unity followed in 2010, describing itself as an "extension of the calculator operating system". It allows the user to mix TI Basic and Z80 instructions in programs, and acts as a psuedo-shell, providing an abort key sequence in the event of an error.
Due to the tedium and the limited amount of memory available, there aren't many programs available for the TI-81. What is available can be found on ticalc.org, where, as of the writing of this article, only 187 programs are archived.