Polaris
Posted: Sun Oct 22, 2023 12:22 pm
Hey guys, first post here.
Any love for Polaris? I didn’t see anything about it in the forum and there’s no core available I guess.
Hey guys, first post here.
Any love for Polaris? I didn’t see anything about it in the forum and there’s no core available I guess.
There is an MRA for polaris in the unreleased folder on github. (space invaders core)
I need to look to see what was missing from that, I know it has no sound so samples and possibly the circuit for the boss plane up/down noise are required.
I should be doing some changes to one of the other games as the daughter PCB has been found and traced out so that needs adding in.
I had a look, it basically works but does not look like it uses P2 controls plus the sound is totally wrong (if it makes any)
Also for some reason the sub 'flickers', not sure why that is, it even does it if you set it to B&W so it draws it in white.
Thanks for the information. I'm gonna test it this weekend and post the results.
I went to your unreleased folder and found a game with a brazilian portuguese name that called my attention: Galactica - Batalha Espacial. OMG I remember that game in the arcade and only just now I could realize it was a Galaxian clone. Interesting! Good memories.
The sound is really wrong and the sub flickers. So do you intend to work on it?
Looking at the core it seems (to me) that it is calling the interrupts back to front (it does one mid frame and one at end frame)
changing that to call them in the opposite order and the flashing sub stops flickering
need to check that it doesn't break anything else in the core (and maybe add some visible screen update to confirm my suspicion)
I made a few changes, updated the SYS files and have completed Polaris.MRA
need to do a pull request, but if someone wants to check this first ...
Polaris is working great thank you !
Flicker: it is still flickering when you move the sub from the center to the right side. On the unreleased version, it is the opposite as the flicker starts when you move the sub from the center to the LEFT side of the screen.
Vertical sub movement: Just noticed it is not smooth in small increments as the horizontal movement.
The findings above may be contributing that sometimes the missile from the sub is not visible before hitting the aircraft.
MRA file: had to change the <rbf>spaceinvaders</rbf> to <rbf>Arcade-SpaceInvaders</rbf> in your file.
With this core, I see shots disappearing in Space Invaders. Especially when shooting from approximately the middle of the 3rd and 4th bunkers. Reverting to the previous version of the core fixes it.
Flicker not caused by that then, will revert and see if I can find another reason - Cheers
As far as I can see, it must flicker on the real PCB (although I guess CRT helps hide this a bit)
It moves the sub on the interrupt driven from the vertical flyback, but if your sub is on the left of the screen, then it flickers as it takes several complete horizontal raster lines to erase and re-draw the submarine. The CPU (at 2Mhz, plus wait states etc.) just cannot do it.
I'm experimenting with different CPU overclocking to see if the problem can be reduced!
(of course, mame draws the entire screen at the start of the flyback, so no flickering. you would have to change the code to draw the screen about 1/4 frame late to avoid the flicker, and that would probably mean something else flickers instead!
I've added a DIP to the Polaris MRA that allows you to 'overclock' the CPU and that seems to reduce the flicker.
It may have other effects as well, but gameplay seems the same to me!
It only affects polaris, and cannot be enabled for any of the other games supported by the core.