EMU7800: A .NET Atari 7800 Emulator

v0.91, June 2009
Mike Murphy, mimurphy@users.sourceforge.net

EMU7800 releases can be downloaded from SourceForge here.

Click here to jump to the Keyboard Mappings.

Click here to jump to the Screenshot Gallery.

Contents

1.0 Introduction
    1.1 Copyright Notice, Disclaimer, License
    1.2 Release Notes
    1.3 Acknowledgements
    1.4 Known Issues
2.0 Installation
    2.1 Prerequisites
    2.2 Installing the Distribution
    2.3 Rebuilding from Source
    2.4 Game Cartridge Information Database (a.k.a. ROMProperties)
3.0 Running the Emulator
    3.1 Keyboard Mappings
    3.2 Game Controller/Joysticks
    3.3 Paddle and Lightgun Emulation via Mouse
    3.4 User Interface
        3.4.1 Game Select Tab
        3.4.2 Settings Tab
        3.4.3 Console Tab
        3.4.4 Help Tab
    3.5 External Command-line Options
4.0 Screenshot Gallery

1.0 Introduction

This is a release of EMU7800, an Atari 7800 emulator implemented using Microsoft's .NET platform. Most VCS (2600) and ProSystem (7800) titles work well, with 2600 support featuring authentic HMOVE emulation, per Andrew Tower's paper "A Small Opus on the TIA." The stars in Cosmic Ark appear without emulation cheats!

EMU7800 runs on Windows 2000 and higher systems. Performance is excellent on recent hardware.

Send me a note if you have questions or feedback. Enjoy!

1.1 Copyright Notice, Disclaimer, License

EMU7800 is Copyright © 2003-2009 Mike Murphy.

THIS SOFTWARE IS PROVIDED "AS-IS" WITHOUT ANY EXPRESSED OR IMPLIED WARRANTY. IN NO EVENT WILL THE AUTHOR BE HELD LIABLE FOR ANY DAMAGES ARISING FROM THE USE OF THIS SOFTWARE. PLEASE SEE THE ENCLOSED "LICENSE.TXT" FILE FOR THE COMPLETE LICENSING TERMS.

1.2 Release Notes

v.91

• Updated: DirectX dependencies to SDK March 2009
• Added x86 and x64 specific builds

0.90

• Updated: Replaced SDL.dll with new EMU7800.Direct.dll for better fullscreen and windowed-mode experience on Vista.
• Updated: Corrected sound encoding to reduce audible pops.
• Updated: Fixed minor bugs with new TIA sprite positioning code that affected Demon Attack, Centipede, and Spiderfighter.
• Added: Key bindings reassignment dialog.

0.88:

• Updated: Rewrote 2600 TIA sprite positioning code, resolving some known issues
• Updated: Moved to .NET Framework 3.5
• Updated: SDL.dll to version 1.2.13

0.81:

• Added: WPF Host (Windows Presentation Foundation) for better compatibility with Windows Vista
• Updated: SDL.dll to version 1.2.11

0.71:

• Added: Web browser control on new Help tab, enabling easy reference to this README and online game manuals where defined in ROMProperties.csv
• Fixed: 7800 Emulation: 320B mode corrected to correspond to the real hardware—courtesy of Matthias Luedtke (matthias@atari8bit.de)
• Updated: Moved to .NET 2.0 and Visual Studio 2005
• Updated: SDL.dll to version 1.2.10
• Added: Emulator sleeps after each frame is rendered to reduce superfluous CPU consumption (can be tuned via the Console tab)
• Updated: Better pause behavior—modal functions are still available during pause

0.61:

• Fixed: Emulator continued to run in the background when the window was closed
• Progress meter added so the user has something to watch while large ROM directories are examined
• Added: High Score Cartridge support (7800)—courtesy of Matthias Luedtke (matthias@atari8bit.de)
• Added: Settings are stored in the Win32 registry, so they persist across new versions and recompiles
• Updated: SDL.dll to version 1.2.8
• Updated: Unified distribution into one single .MSI archive, that can build itself

0.60:

• Added: Support for the Stelladaptor controller
• Added: Recognizes the now correct 7800 NTSC BIOS. Old 7800 BIOS is still recognized for now, but a warning message appears on the Green Screen log. Thanks to Mitchell Orman (Mitch@atari7800.org) for the information
• Numerous minor fixes and documentation updates

0.55:

• Added: NOP instruction register dumping (homebrew developer support), activate on the console using cpunop on. Setting will persist between invocations
• Added: Button on the Settings Tab that brings up an openfile dialog to load previously saved machine states
• Added: Double-clicking on the game select tab will immediately start the selected ROM
• Updated: Converted ROM database to a .CSV file: Editable via MS Excel or text editor
• Fixed: PAL 7800BIOS startup
• Added: Command-line ROM invocation to support various emulator front-ends
• Reverted: TIASound to v0.41 version: fixes a sound omission bug
• No changes to emulation were made for this release

0.50:

• "The Truth in Advertising" release... now, most 7800 titles are playable
• Added: 7800 BIOS startup can be skipped
• Added: Both .a78 and .bin 7800 ROMs are supported
• Added: Game state save/restore
• Added: Mouse-based lightgun support, which works correctly for 2600 games
• Added: GUI options for varying emulation speed, etc.

0.41:

• Substituted use of Managed DirectX with the Simple DirectMedia Layer (SDL). Fullscreen performance is now on par with the most excellent Z26 emulator.
• Solved the sound syncronization problem; audio now works perfectly.
• Added: Game controller (joystick) support.
• Added: mouse-based paddle emulation on SDL fullscreen mode.
• No changes to emulation were made for this release.

0.33:

• Fixed: eliminated PIA bugs: no more jittering for Star Fox, Off Your Rocker, Spitfire, Omega Race, Blueprint, and others probably
• Fixed: minor missle/ball positioning TIA bug
• Fixed: booster grip controller now works right
• Fixed: Omega Race rom was being ignored because of its odd size
• Fixed: emulator no longer requires one line of VSYNC; this helps one of the Bowling ROMs and others probably

0.32:

• Fixed: the file picker on the GameSelectTab hung in certain circumstances
• Fixed: Pitfall2 rom was being ignored because of its odd size Cleaned up the distribution by removing some unneeded junk

0.31:

• First major release via SourceForge.

1.3 Acknowledgements

EMU7800 is a derived work of many people. Please let me know should others need to be included in the following list:

• Bradford W. Mott, et al., Author of the Stella emulator
• John Saeger, et al., Author of the Z26 emulator
• Dan Boris, Author of 7800 emulation in MESS
• Andrew Towers, Author of "TIA Hardware Notes: A Small Opus on the TIA"
• Ron Fries, Author of the TIASound library

For all things Atari, including game manuals, tips, and community, be sure to visit AtariAge!

1.4 Known Issues

• Tetris (one scanline fast jitter)
• Challenge: 4311a4115fb7bc68477c96cf44cebacf (doesnt work, needs some illegal opcodes)
• One on One Basketball (7800): Timing maybe fixed, but there are display artifacts
• Xenophobe (7800): flickering/hangs
• Lightgun for the 7800 is inaccurate; a timing problem
• No Supercharger support
• Need Pokey emulation for a couple 7800 titles (Ballblazer and Commando)
• Need Mindlink controller support
• Need to support more illegal CPU opcodes to better support homebrews

2.0 Installation

2.1 Prerequisites

To run EMU7800, you will need to have .NET 3.5 installed onto your Windows-based computer. You can do this for free via Windows Update. To have the capability to build from the included source code, you'll either need the .NET 3.5 software development kit (SDK) or Visual Studio 2008. EMU7800 was originally developed on a machine with a Pentium 4 Celeron 1.7 GHZ processor (a seven year-old system as of this writing.) This was adequate for emulator performance.

2.2 Installing the Distribution

The distribution is made available as an Windows Installer .MSI file. Simply launch it to deploy the software to your machine. A single shortcut will be placed on your desktop to launch the emulator.

2.3 Rebuilding from Source

For the curious, the complete source code is included in the distribution and is located in the src/ folder. The solution and project files are in Visual Studio 2008 format. DirectX dependencies needed by EMU7800.DirectX.vcproj must be copied from the DirectX SDK (freely downloadable.) Helper scripts, COPYDEPS.cmd, are located under EMU7800\Host\DirectX\EMU7800.DirectX\DirectXDependencies to help with this.

2.4 Game Cartridge Information Database (a.k.a. ROMProperties)

In EMU7800, recognized game ROM files have associated properties that determine the proper execution configuration of the emulator. These attributes are stored in the ROMProperties.CSV file, located in the same directory as the executable. Any editor that can work with .CSV files (e.g. NOTEPAD.EXE and Excel™), can be used to update the file.

3.0 Running the Emulator

3.1 Default Keyboard Mappings

3.2 Game Controller/Joysticks

Up to two game controllers (e.g. joysticks) can be used, where the first two found in the device list will be selected for use.

For game ROMs that use the paddle controller, the mouse will be used as input unless the Stelladaptor controller is detected as one of the selected game controllers. In this case, mouse input will be automatically deactivated and the Stelladaptor device will be leveraged for paddle input.

The paddle swapping keys (Q and E) are useful when you are using a set of original Atari paddles, where the "player 1" potentiometer is excessively worn and delivers non-uniform or erratic resistances. Chances are the "player 2" dial has not seen as much action and will perform better.

3.3 Paddle and Lightgun Emulation via Mouse

On paddle games, the mouse can be used as the paddle controller. Sensitivity is currently not configurable. The mouse is also be used for lightgun games. Look for a small white dot that indicates where on the screen the "lightgun" is pointed at.

3.4 User Interface

3.4.1 Game Select Tab

The number of ROMs recognized in the roms/ directory is displayed in the lower left corner. To select a new directory, click the Select ROM File button, and navigate to the ROM directory of your choice. When a ROM file is selected, the rest of the directory contents will be scanned and will be presented for subsequent selection.

By default, .bin files will be displayed in the Open File dialog. To show .a78 files, use the File Type drop-down.

3.4.2 Settings Tab

There are several settings that can be adjusted on this tab. Settings will saved, so they will not need to be set again every time the program is launched.

• Host Select: There are three hosts available to run the emulated machinery. They are: Windows (GDI), DirectX (DX9), and DirectX (DX9 Fullscreen). The Windows (GDI) host is not the best for game playing, but is good for emulator development and testing. It does not operate in full-screen mode, and not all controller features are supported. Further, video performance degrades proportional to the amount of differences between frames. For the best game-playing experience, choose one of the DirectX hosts.

• Frame Rate Adjust: Default framerate for NTSC (N. American T.V. standard) games is 60hz, while the default framerate for PAL (European T.V. standard) games is 50hz. Should you find that your computer is not fast enough to run the emulator, you can adjust the framerate down as appropriate. Persistant audio popping indicates the sound queue is underflowing—indicating the emulator is unable to run fast enough to keep it filled. Note that reducing the framerate also scales down the audio playback frequency accordingly, so the audio pitch will decrease. Audio playback is used to throttle the display framerate—so both are tightly coupled.

• Skip BIOS (7800 Emulation): The real Atari 7800 executes BIOS code on machine startup. To do this on the emulator, the BIOS ROM(s) (one for NTSC, and one for PAL) need to be in the current ROM directory and this checkbox needs to be unchecked. If you do not have the BIOS files or just want to skip BIOS execution, check this box.

• Use 7800 High Score Cart (7800 Emulation): For the 7800, there was a cartridge that provided capability for 7800 games to save high score information. Not all games, however, took advantage of this. Set this checkbox to simulate this device—you will also need the associated ROM for this feature to work. EMU7800 will detect the ROM regardless of filename, as long as it is in the current ROM directory.

3.4.3 Console Tab

Events pertinate to the execution of the emulator are logged to the Console. Commands may also be issued here to access features not available via the GUI. To see what is available, enter ?.

3.4.4 Help Tab

The Help tab features an integrated web browser control. Two link controls are available, located at the bottom of the control. The README link references this README file on the local system. The Game Help link varies dependent upon the currently selected game, and is intended to reference original game instruction manuals, available online. At the time of this writing, not all games have help URLs defined. URLs can be specified in the ROMProperties.csv file, and more will be included in subsequent EMU7800 verisons. Standard web browser features, like the Back button and Refresh, are available by right-clicking in the browser window.

Note that when the Game Help link is clicked, it will "disable" to indicate the page is loading. It will "re-enable" once loading is complete. If no Game Help URL is available, the link will not be visible.

3.5 External Command-line Options

To support various emulator front-end programs, EMU7800 can be launched with a full filename provided as a command-line argument:

EMU7800.exe "EMU7800 installation directory\roms\OYSTR29.BIN" "DirectX (DX9)"

Should the ROM file not be found, be unreadable, or not recognized, the GUI interface will be launched as normal. Clicking on the Console Tab will show the reason for the failure. Otherwise, the ROM will be run immediately.

4.0 Screenshot Gallery

Atari VCS (2600) Titles:

Atari ProSystem (7800) Titles: