TI-95
# TI-95

The TI-95, also called the TI-95 PROCALC, is a keystroke programmable calculator and was introduced in 1987 by Texas Instruments. It was rather large, measuring 3.7" by 8" by 1" and had a 16-character alphanumeric display for the main display, and a set of 5 3-character displays for use as menu items. It had 8kB of onboard RAM, capable of being partitioned by the user between program steps for the built-in program editor, numerically-labelled registers, and file memory. It could also be connected to PC-324 compatible printers. The calculator came with a hard carrying case which closes around it. Compatible ROM and extra RAM could be placed in the expansion slot in the upper right corner of the device, which came from the factory with a dummy protector cartridge labelled "ROM/RAM". Texas Instruments would release three compatible ROM cartridges, one containing advanced mathematics functions such as the Gamma function and Newton's method labeled Mathematics, a second containing statistics features such as the Normal and Student's t distributions and various statistical tests labeled Statistics, and a third containing functions and data on common industrial chemicals labelled as Chemical Engineering. An 8kb RAM expansion cartridge could also be placed into the cartridge slot, and RAM cartridges could be given names to allow a user to have multiple cartridges, each with its own library of custom-made functions. The calculator also supported the use of a cassette tape drive to store programs. Programs are entered into the calculator's memory as a keystroke program, in which the user effectively records a macro which is played back when the program is run.

## ROM Cartridges

Several ROM cartridges were offered for sale alongside the TI-95 to support several different disciplines. These cartridges came with manuals detailing the operation of their functions, as sometimes the limitations of the TI-95's design made the use of the various programs obtuse.

### Mathematics Library

The Mathematics Library cartridge contains 24 programs, such as:

* Complex Number support
* Limited matrix math support
* Function interpolation
* Numerically solving differential equations
* Coordinate transformations between rectangular, spherical, and cylindrical coordinates
* Numerically solving for the roots of equations
* Numeric Integration
* Gamma Function

In programs allowing for calculations using user-supplied functions (for example, the numeric integration program or the root-finder), the user must enter these functions as keystroke programs into the calculator's program memory, which are then used as subroutines by the library's programs. These programs generally give answers within the maximum precision of the calculator, except with some iterative processes such as root-finding, where only a limited precision can be expected.

### Statistics Library

The Statistics Library cartridge contains 25 programs, designed to help statisticians. These programs include:

* Several statistics distributions, such as the Normal and Chi-Squared distribution
* ANOVA tests
* Paired and unpaired t-tests for significance
* Several common non-parameterized tests, such as the 2-way goodness of fit test, and Kendall's Tau test

Only the inverse Normal and Weibull distributions are included with the library, and the significance tests included are limited to the paired and unpaired t-tests.

### Chemical Engineering Library

The Chemical Engineering Library was designed to assist industrial chemical engineers in their workflows, by including a large library of 261 commonly-used organic compounds which can be looked up by an ID number accessible from the manual, as well as from a small guidebook included with the software package, designed to fit inside the calculator's hard carrying case, though any other chemical can be used by manually inputting the various properties required for individual calculations. The software includes programs related to thermodynamics, as well as more specific programs related to common procedures such as distillation.

