Four-Point Smoothing with FPP-12

This document details a PDP-12 computer program designed to perform four-point least squares quadratic smoothing on an array of 4095 data points using the FPP-12 (Floating Point Processor). The program is notable for its ability to operate on data stored as standard 12-bit words by floating, processing, and restoring the values, which significantly saves core memory compared to traditional methods.

Key advantages include:

• Efficiency: It achieves a run time of 10 seconds to smooth 4095 points, compared to 4 minutes and 15 seconds using the standard DEC software floating-point package.
• Visual Feedback: Because the FPP-12 operates in parallel with the PDP-12 CPU, the smoothing process can be observed in real-time on the CRT display.
• Memory Optimization: The use of single-word addressing and efficient floating-point conversion reduces core memory requirements by two-thirds for data storage and by half for program residency.

The document includes the complete assembly language source code (written in LAP6) and a symbol table. A note is provided indicating that a more versatile 8-point smoothing routine is available under DECUS No. 12-73.