Product Design

This page provides links to a series of product design pages, showing how the emulator was constructed and providing information in sufficient detail that, I believe, any of the more criminally insane programmers among us could build their own emulator.

The following subjects are presented. All material relates to current versions of the emulator; if you are running the frozen r4 you may note some differences.

• system architecture — describes the overall design of the emulator, showing how all the pieces fit together and how data and time flow through the emulator. If this is your first look at the H8 emulator, this is the best place to start.

• time — a discussion of time: how we define it, create it, and distribute it to time consumers;

• performance — a discussion of the performance characteristics of the emulator, with a presentation of test tools and benchmark results;

• h8 processing — a poorly named but vital module that glues the 8080A to the emulator's I/O and interrupt structure;

• 8080a emulation — covers instruction dispatch, registers and flags, memory write protection and interfacing to I/O;

• i/o package — talks about I/O interfacing and 825x emulation;

• pam/8 gui — discusses keypad and keyboard handling, LED update and sound;

• h-17 disk system — details the operation of the H-17 Disk System in fine detail;

• h-19 terminal — describes the H-19 Terminal in detail, including all function key sequences and output escape sequences;

• serial i/o — describes the Serial I/O processes: printing, Macintosh bidirectional file transfer and modem support;

• tape i/o — describes the implementation and operation of the PAM/8 cassette tape emulation.

I would be proud to accept and will gratefully acknowledge any errors, gross omissions or outright lies that you spot on these pages. I want this material to be accurate.

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