<![CDATA[FPGA Arcade — Arcade]]> https://www.fpgaarcade.com:443/punbb/index.php Thu, 01 Nov 2018 16:21:59 +0000 PunBB <![CDATA[Scramble inaccuracy - looking for some history...]]> https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=1354&action=new Update,

I modified the code and two fire buttons work fine.

That and using the correct ROM version fixed my problems.

Thu, 01 Nov 2018 16:21:59 +0000 https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=1354&action=new
<![CDATA[Bronze age Atari games]]> https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=1346&action=new I worked on Subs more last night and got all the sounds done except for the sonar ping. I think the LFSR in the manual is either drawn incorrectly in error or it is deliberate obfuscation to thwart copycats because when I code it as the schematic is drawn it sounds terrible. Instead I ended up doing it the same as the Sprint games and Ultra Tank which I already knew sound good and that seems to have done the trick. The next time I go to my friend's place I think I'll bring along a scope and an audio probe and have a poke around the board in his Subs to see.

So now the ping I'm going to have to think about. It produces a 1kHz sine wave that starts at full volume then decays linearly to silence over a period of about 1 second, with the envelope modulated by the random noise signal. I haven't quite decided how to go about this, I'm leaning towards synthesizing a pure sine wave and then work out a way to control the envelope.

It will be cool to get this game done as it's one that isn't emulated properly by MAME. It really needs two separate monitors otherwise you can just look at where your opponent is at any time and it takes away the fun. It also needs the overlays on the screens or it looks rather bland.

Fri, 08 Jun 2018 00:55:07 +0000 https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=1346&action=new
<![CDATA[Centipede]]> https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=1322&action=new ah cool thanks!

Wed, 20 Sep 2017 20:08:02 +0000 https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=1322&action=new
<![CDATA[Xevious]]> https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=1215&action=new Man I still remember the "music" in that game, it could drill a hole in your head. Aside from that it's fun, there used to be one in the hallway at a past employer that I would play occasionally over lunch.

Sun, 29 Jan 2017 19:33:53 +0000 https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=1215&action=new
<![CDATA[Asteroids hardware]]> https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=1213&action=new I'd set this aside for a while but recently started playing with it again. Anyone interested in coding the missing sound effects from the original Asteroids? I tinkered with that for a while but was not happy with what I was able to get. Deluxe uses a POKEY, the original has additional analog circuits for the saucer sounds.

I still have no idea why Lunar Lander won't run either, everything looks fine in the HDL and simulating it things start out ok initializing the RAM and whatnot then the code runs off into the tumbleweeds and the watchdog trips. I suspect there's something stupidly simple that I'm overlooking.

Thu, 12 Jan 2017 05:14:42 +0000 https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=1213&action=new
<![CDATA[Replay Arcade Games Status]]> https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=543&action=new Once I get the framework up, it would be great to get some help with the website!

Wed, 30 Sep 2015 09:57:01 +0000 https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=543&action=new
<![CDATA[Pacman Core How-to]]> https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=541&action=new We have an OSD menu option for INFO, I can fix this. Good idea.

Mon, 28 Sep 2015 08:19:00 +0000 https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=541&action=new
<![CDATA[Sega's 'SuperScaler' arcade hardware: realizable?]]> https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=490&action=new MikeJ wrote:

This is probably the easiest to reproduce - however in my experience untested often means bust, and that's no good for reverse engineering. Cheap though!

I usually still take them (if cheap enough and schematics exist), because they are often very easy and inexpensive to fix.

If not, it is always good to have some spareparts, especially if the board has several custom ICs hard to find "without board"...

Sun, 07 Jun 2015 19:39:16 +0000 https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=490&action=new
<![CDATA[pokey.vhd]]> https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=463&action=new Hi Mike,

I found another issue with the pokey that I have not fixed.  Do you have a newer version on the SVN?

the problem is with this code:

if (poly_sel_hp(i) = '1') and (poly_sel_hp_t1(i) = '0') then -- rising edge
    tone_gen_final(i) <= not tone_gen_final(i);

if two channels are playing the same tone, it is possible that tone_gen_final(i) starts out in opposite states for the two channels.  Then when they are summed together by:

sum12 := ('0' & vol(1)) + ('0' & vol(2));
sum34 := ('0' & vol(3)) + ('0' & vol(4));
sum := ('0' & sum12) + ('0' & sum34);

Then the two channels will cancel each other.


Tue, 28 Apr 2015 10:25:20 +0000 https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=463&action=new
<![CDATA[Multi game rom images]]> https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=449&action=new Difficult issue.
At least with Replay the ROMs are not part of the build, they just need to be copied to the SD card and are uploaded to the FPGA. It's then up to the end user to source legal copies.

If you look in the pacman directory, the ROMs which would ship are for a demo game, and the real ROMs go in directories - pointed at by the ini files.

I would love to come up with a licensing model for distributing ROMs, but it's not been possible so far.

Sat, 21 Feb 2015 08:38:07 +0000 https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=449&action=new
<![CDATA[Bagman (STERN-Valadon Automation)]]> https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=325&action=new Very impressive ! Want to try to replicate learning with a Xilinx hardware.
Would be nice to extend it to DVI, more sophisticated graphics and effects !
I like one article about one of you implementing Tom and Jerry from the
Atari Jaguar !

Sun, 08 Jun 2014 21:01:08 +0000 https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=325&action=new
<![CDATA[Crazy Kong (FALCON)]]> https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=315&action=new Thanks! I think this is also the set I have on my CK board, need to check...

Tue, 03 Jun 2014 19:08:17 +0000 https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=315&action=new
<![CDATA[black widow]]> https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=262&action=new http://spritesmods.com/?art=bwidow_fpga

Here's Atari's Black Widow in an FPGA.  this would require a vector to raster conversion circuit.  I think the author released this as free to use.

Gravitar is a ROM swap.  Space Duel could work with some minor tweaks to the source code.

The designer did a slick job implementing the vector state logic.  instead of using proms, they implemented it as a regular state machine :-).

Wed, 12 Mar 2014 05:35:10 +0000 https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=262&action=new
<![CDATA[FPGA Recreations]]> https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=200&action=new My opinion is that one should try to follow the original hardware as closely as possible, if only to make it easier to make later modifications and additions and refer to the original schematics. As mentioned above the more closely it resembles the original hardware, the more modular it tends to be. Obviously there are some cases where it makes sense to deviate somewhat, taking advantage of the characteristics of FPGAs. Also while it may not be quite right for this topic, I always avoid instantiating any primitives directly, trying to make everything as platform-agnostic as possible. Some projects are very easy to port from one FPGA type to another while others require extensive modifications.

Tue, 24 Dec 2013 21:02:58 +0000 https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=200&action=new
<![CDATA[FPGalaxy - Homebrew Game]]> https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=192&action=new I have the same FPGA dev kit, and would like to
try your code. Can you please share your circuit
for the hardware to interface the Nintendo controller

Thank you in advance !


Sun, 15 Dec 2013 23:41:41 +0000 https://www.fpgaarcade.com:443/punbb/viewtopic.php?id=192&action=new