M-1104 Apr61

This memo describes FRAPCORRECTOR 1, a program developed by Adams Associates, Inc. for Digital Equipment Corporation, dated April 11, 1961.

Purpose: FRAPCORRECTOR provides a way to make symbolic changes (delete, insert, or replace) to a Frap language source tape.

Operation:

1. Correction Tape: Corrections are prepared on a separate paper tape in a fixed format, including:
   • A control character (i for insert, d for delete, r for replace, e for end of tape).
   • An octal number (NN) specifying the count of corrections (01-77).
   • An octal addend (AA) to a symbolic address (00-77).
   • A symbol (SS...SS) to determine the starting location for the change.
   • For i and r commands, the actual correction lines follow this control information.
2. Two Passes:
   • Pass 1: Reads the correction tape and stores all correction information in core memory.
   • Pass 2: Reads the original Frap language tape, applies the stored corrections in order (which must correspond to the tape's symbol and addend sequence), and produces a new, corrected Frap input tape.
3. User Interaction: The user starts the program and interacts with it at various halts by selecting options via sense switches (e.g., tape code, printing, multi-tape processing) and depressing a "continue" button.
4. Completion: The program outputs a message indicating "CORRECTIONS APPLIED" if successful, or "ONLY NN CORRECTIONS APPLIED" if errors prevented some corrections from being made. The end of a Frap tape is denoted by "ENDcr".