High Score Save


 Overview

This is a high score save for Arkanoid II - Revenge of DoH by Taito (with some hardware from Seta). For this save you'll need to change one ROM and replace one RAM chip with a non-volatile RAM. The RAM chip you need to replace is unlikely to be socketed, so you'll have to remove the RAM and install a socket for the new NVRAM. This one is bit harder to do than previous saves, as you'll be socketing a 28-pin chip on a multi-layer PCB. If you don't have the soldering skills to do this, please find someone who does to do it for you. An experienced tech can do the job in under 10 minutes. You perform these modifications AT YOUR OWN RISK!!!

 How It Works

This score save was fairly simple to do. It's a Z80 based game with no encryption (although it does employ some sort of protection). I modified the RAM initialization routine so that it stopped clearing when it reached the region containing the high score table (I didn't have room to write code to clear the region after the table, but that seems to be OK). I changed the routine that sets the gameplay high score to read its value from RAM rather than use the default contained in ROM. I didn't have to change the high score table reset code at all. It already has a check to see if the table is valid before it overwrites it with defaults! To force the game to reset the scores you just have to corrupt the table, which can be accomplished in test mode.

To reset the high score table:

The gameplay high score display will initially not be correct (it will correct itself on the next boot). If that bothers you, just wait until you see the high score table and then reset the game (power cycle or use the little reset button on the PCB next to the edge connector).

Due to the protection, I had to make two versions of the score save; one for the "World" version and another for the "US" version (licensed to Romstar). You can tell which one you have by the label on the EPROM at position 11C:

If you use the wrong version the game will still play, but you'll eventually run into a level that has no blocks! And that spells GAME OVER.

The "continue" option on the US version is different from the World version. Instead of just starting the next game at the current level, it allows the player to continue exactly where he left off, adding to his score! So you might want to consider turning that option off (set dipswitch 8 on SWB OFF).

 Installation

1) The 8K static RAM (6264 or equivalent) at location 7C needs to be replaced with a non-volatile memory. If that chip happens to be socketed then this step will be a breeze; just pop out the RAM and plug in the NVRAM. If not, then you'll have to remove the chip and install a socket. NOTE: the pins connected to the power rails (14, 26 and 28) will be more difficult to remove than the others, so you'll likely need to crank your iron up a notch (be careful!).
For the NVRAM you can use a battery-backed SRAM like the Dallas DS1225 or the ST M48Z08. I tried to use a Simtek 16C68 (which would have been sweet!), but the board just didn't like it.

Once you've got the new chip installed you should test the board at this point to verify that your socket installation is good. The game should play normal.

2) The new high score save ROM (a 27c512 EPROM) installs at location 11C. The socket next to it should be empty, unless the board has been strapped to use two 27c256 EPROMs (which I've never seen). Remove the existing EPROM and pop the new one in. That's it... you're done!



 Kits

High score save kits are built on demand. They contain:

Price is $32 shipped in the US (international shipping available at additional cost).
Please email me to check availability before sending money. Please remember to specify which version you have (US or World).


 Download

For the do-it-yourself'er. If you've got your own programmer you can just download this ROM image and burn it to a 27c512 EPROM.

download the ROM image

Donations via PayPal "gift" payments (to osborn@alum.mit.edu) are always appreciated. Any money received goes right back into my arcade and score save development. Thank you.


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