Higgins ZX Spectrum Emulator Home Page

This ZX Spectrum 48K/128K/+2 emulator is dedicated to provide you the sense of a real Spectrum machine, as it was (and still is) in real life. The stoutness and precision are our major objectives, just like in Snooker.

News

23 May, 2008 - Higgins 8.10 alpha 3 available (changes).

Contents

• Overview
• Screenshots
• License
• Download
• Manual
• Keyboard mapping
• Problems known
• Acknoledgements
• Contacts
• Changes history

Overview

We do not like lots of options, at least until implementation is free from sensible deviations.

The emulator provides complete and precise emulation of:

• Z80 instruction set, including undocumented instructions;
• Flags, including undocumented flags 3 and 5;
• MEMPTR internal register;
• Instruction timings;
• Memory and port access contentions, including IR contentions;
• Floating bus for both odd and even ports;
• The snow effect;
• Multicolor border and screen-area effects;
• Issue 3 EAR socket fall delay at port 0xfe;
• 128K AY sound and screen switching;
• Unrefreshed memory discharge (48K only);
• Sound, keyboard and tape loading.

Known deviations are:

• The output method does not experience a TV interlace;
• There is currently no support for tape saving;
• It's not yet known if the R register got incremented before or after ULA fetch subsequent video cell so there may be a technical deviation from a real machine while the visible matter of the snow effect is exact.

Screenshots

License

This software is a subject to the BSD-like binary license terms:

Download

Manual

To run the emulator just type

./higgins

Generally, the emulator mimics the spectemu user interface with that difference that Higgins use its own communication console. The control keys recognized are the following:

• ESC Shows or hides the console
• F1 Produces a brief summary on console commands syntax
• F2 Saves current state to an (uncompressed) .z80 snapshot
• F3 Restores current state from a .z80 snapshot
• F4 Selects a .tzx file to be the current tape
• F5 Resets the machine
• Ctrl-F5 Changes machine model (also causes machine reset)
• F6 Pauses or unpauses the tape
• F10 Quits the emulator

When using the emulator please keep in mind that all these points are powered by the Not Designed for Game Cheating(TM)^* technology.

Keyboard mapping

All letter and digit keys match their PC keyboard equivalents. ENTER and SPACE work for themselves, left SHIFT works for CAPS SHIFT and right SHIFT works for SYMBOL SHIFT.

Problems known

• Some kinds of TZX blocks are not yet supported;
• The emulator uses video facilities intensively and thus makes the host machine working under somewhat stress conditions.

Acknoledgements

We would like to thank people whose great work help us make this software work properly (sometimes):

• Sean Young for his excellent "The Undocumented Z80 Documented" paper, which gave us a lot of information about how the processor actually behaves;
• Patrik Rak, Philip Kendall and Chris Smith for their research of internal ULA operation;
• Boo-Boo and Vladimir Kladov for their brave experiments with the MEMPTR internal register.

Contacts

We hope this work let you experience the spirit of ZX Spectrum. If you feel something about this work, please let us know at

jhiggins@yandex.ru

Changes history

Higgins 8.10 alpha 3:

• 128K/+2 machines supported, including shadow screen, AY sound, floating bus and precise screen timings and contentions. There is the console command "mode" introduced to control switching between the machines;
• Complete support for .z80 snapshot formats provided;
• The keyboard repetition state now only affects the emulator window itself;
• "Close window" event and SIGINT and SIGKILL signals handling added;
• Plain scan codes handling eliminated so preferred system layout should work properly;
• Machine reset now does not affect tape and console.

Higgins 8.10 alpha 2:

• Sound supported;
• Video refresh rate doubled;
• User console implemented;
• Unrefreshed memory discharge implemented;
• Issue 3 EAR socket fall delay (port 0xfe) implemented.

Higgins 8.10 alpha 1:

• First alpha version.

The latest version can be obtained at

http://jhiggins.narod.ru/

This page last updated 16 May, 2008.

^* All trademarks are property of their owners.