TISA

This document describes TISA, a Time Independent Spectrum Acquisition program designed for the PDP-12A computer. TISA acquires asynchronous X-Y data from up to five interfaced instruments simultaneously, displays this data on a scope, and stores it on LINCtape. It supports data rates up to 2 milliseconds per point. The program requires a PDP-12A with at least 4K core, a KW12A clock, and the LAP6-DIAL (version 2) tape.

TISA operates in three modes: Setup (for defining experiment parameters), A/D (for data acquisition), and Pause (no data acquired). Users interact with TISA via sense switches, knobs (for controlling data display), and keyboard commands. Key functionalities include:

1. Setup Mode: Allows users to define parameters like the number of instruments (up to five), sampling frequency, and starting points. Parameters can be loaded from LINCtape or entered via keyboard.
2. Data Acquisition: Collects 10-bit Y-axis data based on X-axis pulses (either analog potentiometer increments or clock channel interrupts). Acquisition stops upon reaching a predefined number of points, a user halt, or a significant decrease in the X-axis potentiometer reading.
3. Data Buffer Display: Visualizes the acquired data using a "moving window" (controlled by Knob 0) to view 512 points of the data buffer, a "cursor" (controlled by Knob 4) to highlight specific points, and displays their X-Y decimal coordinates.
4. Keyboard Commands: Provides various commands to control instruments (halt, go), manage the display (polarize, freeze), write data to LINCtape, enter setup mode, and load other programs like CATACAL or MAGSPY.
5. Instrument Interface: Details the pin assignments and rules for connecting external asynchronous instruments (using potentiometers or shaft encoders for X-axis input, and analog channels for Y-axis input).

The document also includes a glossary of terms, internal descriptions of routines, and flowcharts.