M-1103 May61

This document, an Interoffice Memorandum (M-1103) dated May 24, 1961, from Adams Associates, Inc. to the PDP Distribution List, describes a debugging aid called "Analyzer 1" for PDP computers.

Purpose: Analyzer 1 generates a detailed program listing. This listing includes:

• Memory location
• Mnemonic operation code
• Octal contents of the location
• A cross-reference of all instructions that refer to that specific memory location, along with the memory locations of those referring instructions.

It can handle approximately 1750 references or about 3000 instructions (for programs that do not contain shift, operate, skip, or in-out instructions, which do not generate references).

Usage Workflow:

1. Start the Analyzer program at memory location 0000.
2. Place the program tape (which must be in "read-in mode") to be analyzed into the reader and press the "continue" button.
3. If the program has multiple sections, turn Sense Switch 2 ON after each section (except the last one) and press "continue."
4. After the last program section, turn Sense Switch 2 OFF, re-insert the program tape into the reader, and press "continue" again. This second pass generates the actual listing. A final "continue" with Sense Switch 2 OFF might be needed for references not found on the input tape.
5. Sense Switch 1 controls the output:
   • ON: Output is punched for an off-line Flexowriter.
   • OFF: Output is printed on the on-line typewriter.

Special Notes & Troubleshooting:

• Input tapes must be in "read-in mode." Programs created with the Punch Load Package need to be re-punched in read-in mode (e.g., using PRIM).
• A known issue with the paper tape reader can cause premature halts at location 0200 (erroneous end-of-tape). To remedy this, back up the tape (at least 3 lines) until '32' appears under the read head, ensure Sense Switch 2 is ON (if off), and press "continue."

The document concludes by acknowledging that the Analyzer was supplied to DEC by Charles W. Adams Associates, Inc.