M-1094 Nov60

This preliminary interoffice memorandum, M-1094, dated November 22, 1960, details the Sine and Cosine Subroutines for the PDP-1 Computer.

Originated from code supplied by Chas. W. Adams Associates, Inc., and distributed by Digital Equipment Corporation (DEC), the document describes fixed-point subroutines for calculating sine and cosine of angles:

• Argument Format: An angle is represented with a sign and three binary integer positions.
• Result Format: The result's binary point is immediately to the right of the sign.
• Argument Range: The input angle can vary from -2π to +2π radians.
• Result Range: The output value ranges from approximately -1.0 to +1.0 (specified as -.377777 to .377777 in octal).
• Dependency: The subroutines rely on a separate "modified multiply" subroutine.
• Calling Sequence: Instructions L10 and JSP are used, requiring the address of the angle in radians and the starting address of the sine or cosine routine.

The memorandum provides the complete assembly language listing for both SINE and COSINE routines, including internal labels and numerical constants like PI/2 (PO2) and 1.0 (ONE).