All Things Arcade Homebrew

[Hurray Banana]

Nice, 2023 is the year for me to get back into this myself.

Finish my pure tile snake game and get the Spin Pac Dizzy prototype finished.

 

[Hurray Banana]

Wondering if there's anything similar out there for the Galaxian hardware, I like the idea of more sprites to throw around....

with Pac you can You can easily get 12 sprites on screen, 18 at a push

The scroller on my pixel level scrolling demo has 12 sprites on screen

[tube]hSDAHflZj6s[/tube]

 

[arlasoft]

Nice - changing sprite registers mid-frame?

 

[Hurray Banana]

Nice - changing sprite registers mid-frame?

No the hardware doesn't support that style of multiplexing, one shot deal. You have to use an interlacing update of the sprite registers

 

[arlasoft]

Have you got any sample code for some simple SFX? I can't seem to get a peep out of it no matter what I write to the voice registers and the sound enable register. Just launched the midway roms to check it wasn't an issue with Mame.arlasoft2023-01-06 18:12:13

 

[RaveN]

Very impressive, reminds me of the old cracktros.

 

[arlasoft]

Nice - changing sprite registers mid-frame?

No the hardware doesn't support that style of multiplexing, one shot deal. You have to use an interlacing update of the sprite registers

Apologies for being a bit spammy, I'm currently making a game for the 48-hour Ludum Dare game jam so if you've got any basic SFX code that would be a big help, as I posted above I can't currently get so much as a beep out of it.

arlasoft2023-01-07 17:36:17

 

[Hurray Banana]

Ms Pac dissassembly (never looked at it myself yet - was going to use it to get my head round sound)

https://www.ukvac.com/forum/data/uploads/1527/mspac.zip

 

[arlasoft]

Thanks, I finally managed to get some sound out of it with minutes to spare thanks to a snippet of code in Scott Lawrence's doc. Will probably add some more levels for a post-jam version to make it a more fully-rounded game.

https://arlagames.itch.io/pollen-angel-pacman-hardware

arlasoft2023-01-08 20:58:02

 

[Hurray Banana]

Looks nice

 

[arlasoft]

A question on sprites, if I build roms utilising all eight sprites they appear on MAME. Also a lot of documentation seems to say Pacman has 8 hardware sprites, Pengo only 6.

Scott Lawrence: "You can have 8 floating sprites in Pac-Man, but only 6 in Pengo."
Chris Lomont: "The Pac-Man hardware supports 8 sprites"

Are Pacman PCBs actually capable of this or are the registers just not physically wired up because the game itself only needed 6? I see in your code you skip registers 0 and 7 and use the middle 6.

 

[philmurr]

Mame will display all 8 sprites in Pacman

A real Pacman board will only display 6 sprites (from memory it doesn't show the first or the last)

 

[Hurray Banana]

Phil is correct a PAC board only displays sprites 2 to 7

 

[arlasoft]

Thanks guys, what an annoying restriction!

So if I was to alternate sprites at 30hz, how convincing does that look on a CRT thanks to the phosphor fade? I haven't had or for that matter seen a CRT since the 90s.

I've always avoided doing it on a C64, mainly because there's not a lot that can't be achieved with multiplexing, but I've got it in a 2600 port of Bomb Jack I've been working on and I don't know if I like it, certainly on modern displays.

My end goal is to write a game good enough to justify buying a real PCB, CRT monitor and burn some roms.
arlasoft2023-01-14 17:40:32

 

[Hurray Banana]

You get a nice transparent effect. You can see it in my pixel demo video. Just make sure you prioritise filling the sprite registers at the start of vsync. Decouple the sprite display from any logic. Then the game code can still run at 60 Hz

 

[Hurray Banana]

Also you may wish to dedicate the main sprite and only interlace the other 5.

Low speed interlace is also a great way of doing a few effects.

I've even messed with this in tic 80, as that doesn't do transparency Hurray Banana2023-01-15 21:44:06

 

[Sokurah]

Hi Guys,
Long time, not see
I'm currently having a bit of fun coding for the Pacman hardware, and I've run into a "need".
So, sprites and tiles can have 4 colors, and black is (mostly?) always color 0 and transparent, but I'm wondering: "can I have a block that's solid black, but which isn't transparent?", so like it's solid color 3, but with a black palette that you can't see through it ... and how would I go about that?

 

[Hurray Banana]

What happens if you choose one of the all black pallettes, does it still show pen 0 as transparent, or are all the pens when black rendered transparently?

If not then you could build a single sprite tile using pen 1, 2 or 3 and select one of the all black pallettes.

Can't test this at the moment as my dev environment is borked, need to get it up and working over the next few days

 

[Sokurah]

What happens if you choose one of the all black pallettes, does it still show pen 0 as transparent, or are all the pens when black rendered transparently?

If not then you could build a single sprite tile using pen 1, 2 or 3 and select one of the all black pallettes.

I placed sprite 63 on the screen and manually just edited the last 64 bytes of the ROM into random numbers (seemed like the quickest way to test it) and all that was black became transparent, and I tried that with the first 32 palettes - many of which are all black ... and I didn't get the result I wanted.
I was hoping I could just edit the palette, but it doesn't seem like it's possible ... but I wanted to hear if someone else had other experiences.

 

[Hurray Banana]

The only other thing you could do is edit the colour prom to give a dark colour for one of the pens, they are rrrgggbb i think. Aaron giles discusses it in this link. It's not going to be black though.

Aaron giles

The only other thing you could do is have a background colour other than black, the dark blue of the ghost pupils maybe and build your tiles around that