AIPOS Build/Init Internal Description

This document, "AIPOS BUILD/INIT Internal Description," dated May 15, 1971, provides a detailed internal description and operational guide for the BUILD and INIT programs within the LDP (LINC-DEC Pdp) system.

The core functionalities are:

1. INIT (Initialization): This program is used to prepare LINC tapes and disks for the LDP system. It achieves this by writing necessary index information and the AIPOS system (Monitor and Job Control) onto the volume. The process is highly interactive, requiring the user to specify:

   • The mnemonic unit code for the device to be initialized.
   • A volume identification (up to ten characters).
   • The number of index blocks to allocate, with guidance provided for appropriate sizing.
   • For LINC tapes, the number of blocks marked on the tape.
   • The source of the system binaries (e.g., copy from another LDP volume, from DIAL-MS binary files, or omit a system entirely).

2. BUILD: This program modifies DIAL binary files to make them compatible and usable by the LDP system. Key user inputs for this process include:

   • The unit and name of the binary file to be built.
   • The starting mode (PDP-8 or LINC), field, and starting address for the primary binary file.
   • Specifications for any optional secondary binaries (like overlays or help frames).
   • The amount of scratch space and the number of working areas the program requires.

The document also outlines the standard binary file structure in the LDP system, which comprises a header block (containing loader information), a primary binary (main program code), optional secondary binaries, and an optional scratch area. It further details the internal routines used by BUILD/INIT, such as MAKBIN (for building binary files), ASK (for user input), GDIAL (for file lookup), CPYFIL (for file copying), CVH (for header conversion), and GET/PUT (for mass storage I/O). A core map illustrating memory allocation and flowcharts for the INIT and MAKBIN processes are also included to aid understanding of the system's architecture and operation.