Instructions Used in the PDP-8 Mode

This document provides a detailed listing of instructions and microinstructions used in the PDP-8 computer operating in a specific mode, categorized for clarity. Each entry includes a mnemonic code, a description of its function, and the execution time in microseconds.

The instructions are grouped as follows:

1. Basic Instructions: Fundamental operations such as logical AND, 2's complement addition, increment and skip if zero, deposit and clear AC, and program flow control (jump, jump to subroutine, in/out transfer, operate).
2. Group 1 Operate Microinstructions: Operations primarily involving the accumulator (AC) and link bit, including no-operation, incrementing/complementing the AC, rotating the AC and link, and clearing the AC or link.
3. Group 2 Operate Microinstructions: Instructions for program control (halt), inclusive OR with the switch register, and conditional skips based on the state of the AC (zero, non-zero, minus, plus) or the link bit.
4. Combined Operate Microinstructions: A more extensive set of combined operations affecting the AC and link, such as complementing and incrementing the AC, loading the AC with the switch register, setting or getting the link, and various conditional skips based on AC and link status.
5. TTY KYBD/READER: Instructions for controlling the keyboard/reader, including skipping on flag status, clearing the AC and flag, and transferring data between the keyboard/reader buffer and the AC.
6. TTY PRINTER/PUNCH: Instructions for controlling the printer/punch, involving skipping on flag status, clearing flags, and transferring data from the AC to the printer/punch buffer for output.
7. Random Access Disc File Type DF32: Specialized instructions for interacting with the DF32 random access disk file, covering operations like clearing and loading disk memory address registers, reading from and writing to disk memory, managing extended address registers, and conditional skips based on disk operation flags. Execution times are specified for both 8-mode and LINC-mode.