M-1095 Nov60

This interoffice memorandum from November 22, 1960, describes a modified multiply subroutine (a "patch") for the PDP-1 computer.

This patch is critical for ensuring correct operation when using sine, cosine, arccosine, or arcsine subroutines, and must be loaded into memory after the main multiply subroutine. It introduces two key changes:

1. Modifies the subroutine's calling sequence.
2. Leaves the right-hand portion of the product left-adjusted in the I/O unit, without a sign.

The memo provides the specific calling sequence and the assembly language code for the patch. The modified multiply subroutine was supplied to DEC by Chas. W. Adams Associates, Inc.