Wednesday, May 25, 2005

Speed Coin

I've had almost no time to finish Space Raider lately, so I thought I'd talk about the history of a game I own - Speed Coin.

As far as I know, I'm the only one with a Speed Coin cabinet. It's definitely a prototype, as the cabinet is made of nice plywood and not particle board. Also, the marquee and control panel are made of colored paper, colored electrical tape, and a blown-up xerox copy of a coin face. My understanding is that it came from Stern when it shut down.

The boardset is a Scramble, with hand-labelled ROM chips inside. Also, the wiring harness is different, since it only requires a 2-way joystick.

When I went to plug this into the Scramble driver in MAME (back in 1999!), I was stymied by the fact that the background was blue in MAME, but black on the "real thing". I traced through the PCB only to find that the monitor was adjusted with the blue gun turned off! When I adjusted it, it matched MAME exactly.

In case you are wondering about the sound, the music sounds kind of muted and noisy on the real thing, just like in MAME.

Last year, I was stunned to play Speed Coin in an arcade in Nashville, Tennessee. It turns out the Ultracade guys added that game to their Multigame system, under "Arcade Classics"?!. I'm sure they used the ROM images I dumped in my basement, and here it was on a machine in another city. Pretty strange feeling.

I really don't think it's a classic. More like "Arcade Relics". :)

Oh well, I'll get back to Space Raider this weekend, hopefully. I have a newly-found JAMMA harness and a brand new RGB-to-TV adapter which should make things easier. With that, I'll be able to take screenshots from actual boards, and compare them with MAME.

Tuesday, May 03, 2005

Space Raider Stars

Well, I found time to make a few more discoveries. The Space Raider boardset is 3 PCB's. Two of them are full size and obviously two halves of the same design. Then, there is a little PCB grafted on top, connected via a 24-pin dip connector, with wires going to the other two boards.

I suspected that this board was the starfield generator. Sure enough, if you unplug it and run the board, the stars disappear. Cool - less work for me.

Then, I noticed something else. Two chips were missing from the board, and it was labeled with the number 8011, unlike the other boards. Maybe this board is from another game? Searching through the MAME code, there is a comment that Universal game #8011 is Zero Hour.

Luckily, a manual and schematics are available for Zero Hour. The starfield board is the same! In Zero Hour, this board provides both color generation and stars. The missing chips in Space Raider disable the color generation part, since that's already on the main board.

Anyways, I added preliminary support for the scrolling stars to MAME, and it looks right. I need to measure a few more things to get the timing exact. When I'm done with Space Raider, I'd like to add the stars to the Zero Hour / Red Clash driver, since it's missing there as well.

As a side note - I hope these posts are interesting to someone. I think it's kinda cool to document the little things that it takes to get a MAME driver right.

Fun with FPGAs - recreating the Atari TIA, Part 1

I have been playing with recreating the Atari TIA chip as used in the original 2600 in an FPGA.  I know this has been done a few times alrea...