M-1109 TIC Jun61

This Permanent Memorandum (No. 1109, June 19, 1961) from Adams Associates describes the Typewriter Inquiry Control (TIC) routine for PDP computers.

Purpose: To provide a convenient method for examining and/or changing words or groups of words in core memory using the console typewriter. All memory addresses and data are handled in octal notation.

Usage:

1. The operator starts the routine (e.g., at address 7777) and types a memory address followed by a delimiter (carriage return, period, tab, or 'j').
2. TIC responds by typing the contents of that address.
3. The operator can then:
   • Type a replacement word followed by a delimiter to change the memory content.
   • Type only a delimiter if no change is desired.
4. Delimiter Actions:
   • Carriage return: Indexes to the next memory address, types its address and contents.
   • Period: Returns the routine to waiting for a new starting address input.
   • 'j' (after an address): Causes the routine to begin execution at the specified address.

Key Features & Notes:

• The accumulator and I/O register are preserved.
• Operator input is conceptually "red" (underlined in the example); routine output is "black."
• Leading zeros in typed addresses/words can be omitted, except when typing a correction word of all zeros (at least one zero must be typed).
• If input errors occur before a delimiter, only the last six characters typed will be recognized.