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Overview

H1SIM is a rudimentary simulator which main purpose is to test developing software using a modern PC rather than the target minicomputer. H1SIM does not emulate the Heritage/1 circuitry but solely its behavior and it does it, not in real-time but at the PC's speed which is obviously much faster.

H1SIM is written in PHP command-interface (CLI) and employs a command-based user interface. The scenario for its action is an internal representation of the Heritage/1 memory (MEM). Different commands are provided to load content into MEM from files or directly from the command interface as if it was entered in the minicomputer using the Console's Entry Switches.

Programs in particular can be loaded from the same binary files produced by the H1ASM assembler. Once in MEM, those programs can be "executed"; the execution results in changes to MEM content that can then be dumped into human-readable (ASCII) files or directly to the standard output for immediate inspection. Programs can also be ran in "step mode".

H1SIM also offers a number of debug capabilities nowadays found in modern debuggers, such as the ability to define break points and watches. Other features include: disassembling to Listing files similar to those produced by the H1ASM assembler, binary file manipulation and others.

Hardware interrupts can be simulated though with certain limitations as we shall see. Peripherals emulation is not directly provided but the program can be extended with custom PHP scripts to implement such capabilities. Guidance for doing so is provided in this manual.