ptrser

This document is an assembly listing for PTRSER, a Paper Tape Reader Service Routine designed for both PDP-6 and PDP-10 computers. Developed by Digital Equipment Corp. in 1969, it was assembled using MACRO V36.

The routine defines crucial system parameters, including bit assignments for the Paper Tape Reader Control Register, special I/O status word configurations, and ASCII character constants. It interacts with various external system routines and manages internal data structures, notably a PTR Device Data Block.

PTRSER's core functionality is orchestrated through a Service Dispatch Table, which provides entry points for operations such as device initialization, release, closing, and output. The routine is responsible for managing paper tape input, handling data buffering (including advancing buffers and checking for block completeness), and supporting different input modes (e.g., binary image). It incorporates comprehensive error handling for issues like checksum errors, parity problems, and device time-outs, ensuring robust operation of the paper tape reader.