LINC-8 Simulator Trap Processor

This document describes the LINC-8 Simulator Trap Processor, a program designed to enable LINC-8 and classic LINC programs to run on the PDP-12 computer, specifically by handling Teletype input/output. The processor uses the PDP-12 Instruction Trap Facility to detect and simulate the execution of LINC-8 Teletype I/O instructions (KBD, TYP, KST).

The program must be loaded into PDP-12 core memory along with any LINC-8 or classic LINC program that uses the keyboard or teleprinter. It operates by identifying trapped instructions, simulating their LINC-8 effects, and then returning control to the user program. A key limitation is that it is not interruptible and cannot be used when the PDP-12 Program Interrupt is enabled.

The document provides detailed instructions for loading, starting, and restarting the trap processor, including various entry points and their functions (e.g., Start 400, Start 20, GUIDE Load). It also explains the internal operation, covering machine state saving, instruction identification, and specific processing for TYP and KBD instructions, which includes ASCII to LINC character code translation.

Furthermore, the document offers comprehensive guidance on adapting the trap processor for custom needs. Examples include modifying it to process additional LINC-8 OPRs (illustrated with an XY12 plotter control example), adapting it for convenient loading from existing GUIDE or LAP6-3L tapes, and suppressing Teletype character echoing. The program occupies specific memory locations in segment 0 and is distributed in LINCtape form.