DRAGON'S LAIR / SPACE ACE COMBO
Developed by Dave Hallock, Jeff Kinder, and Jeff Kulczycki - 9 April 2002
Now you can easily change EPROMs between Dragon's Lair and Space Ace with the flip of a switch. This document will show you the steps necessary to make your own Dragon's Lair / Space Ace combo game.
The existing Space Ace DIP switch settings have been remapped to match more closely with Dragon's Lair. This allows a person to easily change from Dragon's Lair to Space Ace (or vice versa) while retaining all their favorite settings, like free play, amount of lives, attract mode audio, etc. Also, all three skill level selections (CADET, CAPTAIN, SPACE ACE) have been added. Now you can set your skill level for Space Ace via DIP switch! This comes in extremely handy if you are playing Space Ace in your Dragon's Lair game, which does not have the skill level buttons.
NEW DIP SWITCH SETTINGS
As stated above, all of the existing Space Ace DIP switch settings have been remapped. Please refer to this new Dragon's Lair / Space Ace combo DIP switch settings chart for use with the combo ROM images.
VERY IMPORTANT!!!!! If you create the new Dragon's Lair / Space Ace combo EPROMs for another person to use, you must provide that person with a printout of the new combo DIP switch settings. Thank you!!
DOWNLOAD DLSA_COMBO.ZIP NOW!
THEORY OF OPERATION
Dragon's Lair and Space Ace use type 2764 EPROMs which hold 8,192 bytes each. A 27128 EPROM holds 16,384 bytes. By using a 27128 chip, we can fit both sets of data onto one chip. We then use a switch to toggle A13 (address 13 line) to force the chip into two halves (upper and lower). 2^ 13 equals 8,192, so with A13 "ON", the chip read address starts at 8192. With A13 "OFF", the chip read address starts at 0. To put this in a game perspective, putting the switch in the "OFF" position would give you Dragon's Lair and the "ON" position would give you Space Ace.
Take your wrapping wire and measure it out to fit from pin 26 (address A13) on U5 to the other side of the ROM board at pin 26 on U1. On the solder side of the ROM board, carefully solder the wrapping wire at each pin 26 location. Next, solder a small piece of wire to pin 14 (ground) on U1, and solder another small piece of wire to the right leg of capacitor C1. NOTE: Be very careful when soldering this wire across each pin 26. You can cause damage to your ROM board or Main Logic Board if solder gets on any of the neighboring pins.
Choose a location for the switch (see the note below the photos). Solder the wire coming from pin 14 (ground) to the left leg of the switch. Next, solder the wire coming from the right leg of capacitor C1 to the right leg of the switch. Lastly, solder the wire coming from the pin 26s to the center leg of the switch.
Take five blank 27128 EPROMs, and program them with the combo ROM images (U1 thru U5) found in the Download section.
Click on the pictures for a larger view.
NOTE - These photos show the switch permanently attached to the ROM board by drilling a hole through it, but you should leave your original ROM board intact and find another, non-invasive way to secure the switch, such as on a new piece of board fastened into the existing mount. Also, separate multigame products have been developed by LaserCon.
Insert your disc, set your new switch for the proper game (it's a good idea to label the switch positions), set your DIP switches, and start up your game. When you decide to change games, power down, change your laserdisc, and flip the switch.
CUSTOMIZED GAME COMBINATIONS
With a simple DOS command, you can easily combine any 2 ROM sets that you'd like to use with this hardware modification! Using the North American versions of the Dragon's Lair and/or Space Ace ROM sets that are available at this site, thousands of different ROM set combinations are possible.
How to do it:
Extract the ROM image files for both desired sets into the same folder, and at a DOS command prompt, type:
copy /b GameA_U1.bin + GameB_U1.bin Combo_U1.bin
(Replace "GameA_U1.bin" and "GameB_U1.bin" with your actual ROM image U1 filenames for each game.)
This will create a new file, Combo_U1.bin that can be burned onto the first 27128 EPROM.
(The two original 8KB binary files simply get pasted together into one new 16KB file.)
Then repeat that command for all the remaining ROM images U2 through U5. If one game has more ROMs than the other, such as if one has 5, and the other has 4, then just make sure that that game's 5th ROM image gets burned onto the same half of the 27128 EPROM as its others, and then the other half of that EPROM can either be left alone, or filled with "FF"s, or even filled with tasty recipes!
ROM images for Dragon's Lair and Space Ace
can be found in the Tech Center.
(The ROM sets that were combined to create the download file offered on this page are Dragon's Lair rev. F2 and the Space Ace DIP Switch Remap.)
The user is solely responsible for any and all adverse effects resulting from the use or misuse of the information described above, the ROM data, or the EPROMs the data is stored on.
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