No music routines, I don't know how to convert them from PSG to SN. I just started conversion and presentation is already running. I have to convert some parts where I used some bios routines due to my lazyness and implement joystick (I have related routine yet). So I think SG-1000 version (no music/sfx) will be ready in a couple of days. It was fun implementing my ISR for the first time. I only had some issues because Glass couldn't assemble this piece if code (I went mad because I didn't know what were messing things):
Org 0000h
Some stuff
Jp start
Org 38h
Jp isr
Org 66h
Jp pause
I understood thx the debugger...
I had to put ds directive in between org directives... to fix addresses
No music routines, I don't know how to convert them from PSG to SN
Maybe you could load the music files into Vortex Tracker II and modify the chip setup and frequency?
You might have to transpose the lower sections (basslines?) of the music up one octave, as I think the SN lacks the lower registers that the AY has.
I'm just shooting some shit, hope this helps. :)
Well. If you need some controls, VDP, or sound routine. Just tell me.
SG-1000:
Audio output is 7F.
Controller for input is DC.
Another type of control input or output is DE.
VDP hold is DD.
VDP for input and output are BE and BF.
One of the other control holds is suppose to be DF.
ColecoVision:
Audio output is FF.
Controller for input is FC.
VDP hold is FF.
VDP for input and output are BE and BF.
One of the other control holds is suppose to be 80 or C0.
Well, I'm ok on SG-1000 side: I know the ports (used them to mute its sound chip). Code till the title screen already run without problems. Tomorrow I'll start to fix game part (avoiding controls, just to make it run: I have joypad specs but first I want to be sure the game works). To do so I probably have to lower the RAM buffer I'm using: instead od buffering all the screen I'll buffer only alien orde (256 bytes) and plot it directly on nametable with an offset (actually I do the same in RAM, so no provlem to do it in VRAM) fue to only 1 KB of RAM (and there must fit the stack too)
Earth attack is now available for SEGA SG-1000 too. The game (still) lacks the audio part: to add musics and sfx I should study a whole new psg, convert audio format and write a specific asm player (on MSX I use a ready tracker and its asm player) so I don't know if it will ever be added (but never say never). The most difficult in SG-1000 development was the low RAM amount (1KB). I did a lot of thing easily on MSX: buffering the whole screen in RAM, working on that buffer for collision, modifies, updates and then move all data to VRAM. Well, it wasn't possible on SG-1000. And it hasn't a ROM too, nor BIOS. I had to manualy set the Stack, I had to write an Interrupt Service Routine, manually set all VDP registers and so on. And obviously the stack amount lowered the usable RAM! It was really challenging but it was worthy too!
Nice work on converting the game
BTW: if you want to make the game a bit harder, maybe you can make the hitbox of the spaceships a bit smaller. Right now it seems to be very easy to shoot them.
