Pdp-8 Floating-Point System

Summary

This manual serves as a guide for using the Floating-Point System on the Digital Equipment Corporation PDP-8 computer.

Key aspects of the document include:

• Introduction to Floating-Point Representation: Explains the necessity of floating-point math to handle magnitudes that vary widely, maintaining constant significant digits by storing values as a mantissa and an exponent. It details the internal binary format used by the PDP-8.
• Arithmetic Operations: Describes how the system uses a "pseudo" floating-point accumulator (FAC) to perform arithmetic (addition, subtraction, multiplication, and division) via an interpreter. It includes command structures and specific operational mnemonics.
• Input/Output: Details the routines provided for reading decimal input and outputting results in a formatted floating-point decimal style, including support for various flags and control characters (such as the "rubout" function).
• Extended Package: Covers additional functionality, including trigonometric functions (sine, cosine, arc tangent), logarithms, and exponential calculations.
• Program Listings: The latter half of the document provides the full assembly code for the floating-point arithmetic interpreter, I/O routines, and the mathematical subroutines, allowing for implementation and customization of the floating-point package.

The manual concludes with technical specifications regarding the memory storage limits for different versions of the floating-point package (8-5A-S through 8-5D-S) and a cross-reference list for program symbols.