The pros and cons of using JPC to play DOS games

Many of the DOS games on this site have a link that says "Play online" to the right of the download, which allows you to play the game in your browser using a Java-based PC emulator called JPC. Whether or not you should play the game in your browser instead of downloading it and playing it on your computer depends on your situation. There are pros and cons to using JPC.

Cons:

• JPC doesn't emulate Sound Blaster hardware, so the games are limited to PC speaker sounds. PC speaker sound is produced by using a musical instrument that functions the same way as a PC speaker, from a Java soundbank. The only reason it sounds different is either because it is sped up/slowed down due to JPC being too fast/slow, or due to the smooth changeover between notes that the midi gives you, or, most importantly, due to the minimum duration enforced by the midi system for a note. Those technical limitations mean isn't always faithful to the original sound. I'm leaving sound enabled for the benefit of anyone who may enjoy it. If you find it annoying, you can turn off sound in the game, or you can turn your speakers down or off.
• JPC doesn't include "slowdown" software, so some games may be too fast to be playable.
• Classic DOS Games can't use JPC to emulate Win16 games because a copy of Windows 3.1 would have to be added to the image. Making a copy of copyrighted software available for use online is just as illegal as unauthorized sales or distribution of that software.
• You don't retain a copy of the game on your computer, which also means that you can't save your progress in games that let you save.

Pros:

• JPC will run games on any Java-enabled browser, allowing you to play DOS games on a wide variety of computers and internet-enabled devices.
• JPC allows you to play DOS games in environments where you don't have the rights to save data to a hard drive.
• JPC is ideal for educators who want to allow their students to play educational games on school computers, where they may not have the ability to install new software.
• JPC is great for people who don't have the technical knowledge to install software or use a DOS emulator if necessary.
• JPC allows you to try a game before deciding if you want to download a copy to your hard drive.

DOSBox is still the recommended method of playing all of the games on this website. The emulation is more accurate, more games are supported, and games can be played with music and sound. A lot of the games on this site play perfectly in JPC, especially games from the EGA era, before games started using protected mode, but after games were designed to run on an 8088 running at 4.77 MHz.

Technical support

General

JPC sometimes displays a black screen for a long time. Most of the time this is simply because of lost performance due to emulation, and patience is all that's necessary.

PC speaker sound is approximated using musical instrument from a Java soundbank, which means that aren't very faithful to the original sound. Chopper Commando sounds quite good. Some games, most notably the Lemmings games, just play a high-pitched sound all the time. Sorry about that. Just turn your speakers down or off if it annoys you.

Abuse

The game may appear to freeze when you try to start a new game, but it simply takes a long time to load. Just be patient.

Alone in the Dark

You must run "Configuration" before "Game". Just press Enter on all three configuration screens and the game will run fine.

Arctic Adventure/Pharaoh's Tomb

The game is essentially "paused" unless you are pressing a key. To advance the action at times when you don't want to move, just press down. To start the game in Pharaoh's Tomb (the menu screen is unreadable), press E.

Bio Menace

Although it looks like Bio Menace stalls at the load screen, press any key when it says "Initalizing, please wait" to begin playing immediately.

Caves of Thor

Having the music on is probably going to be very annoying. Press S to scroll through the sound options until music is off and sound is on.

Commander Keen: Goodbye Galaxy and Commander Keen: Aliens Ate My Babysitter

To fix the graphical errors, go to the Options menu, select Configure, Options, and select SVGA Compatibility. Then go to Sound and select No Sound Effects to prevent the game from crashing during sound effects. The game is now fully playable, but slow.

Hugo II, Whodunit?

The game appears to crash after it loads, but type "exit" to return to the game. There's nothing you can do about the flickering, though.

Keen Dreams

The game appears to stall while loading, but just press the spacebar when it says to "Please standby" and you should be able to play within seconds.

Mouse games

Somes when playing games that use the mouse, such as Mah Jongg games, the mouse will only be able to move around a small portion of the screen before jumping out of the game window and back into your browser. Set mouse sensitivity to maximum and the mouse should move at the same speed in the game window as it does in your browser.

FAQ

Q. Not all of the games on the site are available on JPC. Why did you choose the games that you chose instead of the really awesome games that you haven't added yet?

A. I added as many games as I could. For one reason or another, some games simply don't work in JPC yet. For instance, JPC doesn't play any games by Soleau Software for some reason.

Q. Some of the games don't work! Why did you make them available in JPC if they don't work?

A. All of the games will at least start, though some have difficulty getting "in-game". I left them online for a few reasons. First of all, they might work in the next version of JPC, and they'll already be online when the time comes. Second, this will allow visitors to see how the games run in JPC so that they can submit bug reports. Finally, some of the games may actually work once I change the config settings, and others might work if I added slowdown software to the image.

Q. If there are games that will work simply by changing the config settings, why didn't you do that before putting the game online?

A. I had a lot of games to add to the site, and I apologize if I overlooked a really obvious way to make any of the games work. If you know of a way to get any of the games working, please let me know.

Very important!

I didn't write JPC, and I can't provide any support for JPC. If you want to submit a bug report, offer to help with the project, or thank the people who made JPC, go to the JPC project's homepage.