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.

13 comments:

Anonymous said...

This is good news indeed.
It is interesting to me! Though I'm not the type of person to post often, I do check this blog on a daily basis.

Radwar

URherenow said...

This stuff is interesting to more people than you know...

Keep up the good work!

Roy Fokker said...

I have always found the technical articles/posts to be the most interesting thing about visiting the websites of MAME devs. Granted, I don't understand everything because I am not an electronics genius like the devs are, but the logical process that they go through is intriguing and reminiscent of the way a great detective like Sherlock Holmes would solve a mystery. Kudos to you, Frank, and thanks for your hard work and dedication to this hobby which we onlookers benefit greatly from.

Anonymous said...

Thanks for posting your stuff, and yes, people do care and it helps to know how much work needs to be done to get certain details to work! And all the world might see is a "- Starfield fixed" line, apparently trivial, but now we know better.

Anonymous said...

Hey!!! Don't think that getting a few responses from ppl will mean that you aren't being read (or that we don't care). Just think that some of us reach your blog once per day, and for some of us, is pretty interesting to read good notes, infos, etc about your work as mamedev.

It's just that many of us aren't good to write about electronics or cars.... :-)

Anyway keep up the good work!

J.

BobBorakovitz said...

Good stuff, I always like to read how emulation works & how you guys crack this stuff!

Troy said...

I read most Mamedev blog's on a daily basis to see what's new and interesting. - it's the nearest I'll ever get to emulating a board, so I appreciate your technical insight! Keep up the good work.

Cyberfix said...

I find any news, related to MAME, very interesting. I check all of the links on Aaron's page regularly to look for more information. I just wish Charles would update again too. Thanks for your updates.

Anonymous said...

There are a few of them that aren't linked at Aaron's blog.

Here they are:

Dox Mame & Mess WIP:
http://www.slanina.pl/mamewip.html

Kale WIP (Angelo Salese):
http://www.citylan.it/kale/

Reip's MAME WIP:
http://www.citylan.it/reip/

Bryan's MAME WIP:
http://www.vcmame.net/wip/

Ville's Development Log:
http://www.mameworld.net/vlinde/

Guru's (Know about what's currently being dumped):
http://unemulated.emuunlim.com/

Anonymous said...

There all linked from the http://www.mamedev.com site.

Except for Ville and Guru.

Anonymous said...

I find all the mame dev's blog sites all good reading. Because you get a feel on what the developers are doing and what lengths they go to for preserving titles.

Anonymous said...

Of course it's cool! I program just a little so your post other MAme dev post help to increase my knowledge of hardware/software interaction. Thanks!!

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