I was never completely happy with the Phoenix high score save kit I made over 3 years ago (http://www.ukvac.com/forum/phoenix-high-score-save_topic353371.html). It was a bit clunky and could still cause issues because of the way Phoenix accesses its RAM. Also it didn't have a proper high score table allowing you to enter your initials. Phoenix is still one of my favourite games though hence my obsession with it...
So fast forward 3 years and I wanted to get things right. First off, Phoenix has almost ZERO spare ROM space, so to do something properly I needed to add some ROM. Then to get over the RAM addressing issue, I wanted to have some properly addressed non-volatile RAM. Finally I wanted a simple plug-in solution with no soldering.
So that involved a new PCB design (not simple, as the 8085 CPU uses a shared address/data bus so it needed a bit of thought). Anyway, board designed, GAL programmed and hey it works as a single ROM board, good first steps.
Then about 4 weeks on/off writing the updated game code to give some nice features...
- software-selectable DIPs, covering:-
--- number of lives
--- bonus score
--- coin settings
--- freeplay or not
--- sound in attract mode
--- enable or disable 204K point bug
- attract maintained in freeplay mode
- sound in attract mode (selectable on/off) - this works apart from the background noise in the mothership attract stage where the CPU just can't manage it
- enable or disable the bug that gives ~204K bonus (yes, it's a bug)
- high scores saved to FRAM (no batteries)
- 5 position high score table (there's plenty more NVRAM, just no space on the screen)
- enter your initials (3 letters only, "old-school")
- print "FREEPLAY" on screen in freeplay mode and don't display credits
- don't ask to insert coins in freeplay mode
- you can remove the existing game ROMs from the flaky sockets
There's still some more I'd like to do - I want to sort out the awful collision-detection, the bullets that pass through you, and stopping you from dying when you have definitely pressed the barrier...all to come and there's now stacks of spare ROM space to let me to do all of this. For now though I'm just going to enjoy playing the game with the added features.
Photos (sorry for the blur on the menu and initials entry photos - the background does funky star scrolling so it doesn't look as clear on the photos as it does in reality)...
So fast forward 3 years and I wanted to get things right. First off, Phoenix has almost ZERO spare ROM space, so to do something properly I needed to add some ROM. Then to get over the RAM addressing issue, I wanted to have some properly addressed non-volatile RAM. Finally I wanted a simple plug-in solution with no soldering.
So that involved a new PCB design (not simple, as the 8085 CPU uses a shared address/data bus so it needed a bit of thought). Anyway, board designed, GAL programmed and hey it works as a single ROM board, good first steps.
Then about 4 weeks on/off writing the updated game code to give some nice features...
- software-selectable DIPs, covering:-
--- number of lives
--- bonus score
--- coin settings
--- freeplay or not
--- sound in attract mode
--- enable or disable 204K point bug
- attract maintained in freeplay mode
- sound in attract mode (selectable on/off) - this works apart from the background noise in the mothership attract stage where the CPU just can't manage it
- enable or disable the bug that gives ~204K bonus (yes, it's a bug)
- high scores saved to FRAM (no batteries)
- 5 position high score table (there's plenty more NVRAM, just no space on the screen)
- enter your initials (3 letters only, "old-school")
- print "FREEPLAY" on screen in freeplay mode and don't display credits
- don't ask to insert coins in freeplay mode
- you can remove the existing game ROMs from the flaky sockets
There's still some more I'd like to do - I want to sort out the awful collision-detection, the bullets that pass through you, and stopping you from dying when you have definitely pressed the barrier...all to come and there's now stacks of spare ROM space to let me to do all of this. For now though I'm just going to enjoy playing the game with the added features.
Photos (sorry for the blur on the menu and initials entry photos - the background does funky star scrolling so it doesn't look as clear on the photos as it does in reality)...
