Space Invaders clone | MSX Resource Center (Pagina 8/9)

Van TaylorsEverythingChannel

Champion (415)

17-01-2021, 01:55

If you need another way, look at what I did.

As you see, that's how I did the changes.

Van thegeps

Paragon (1194)

17-01-2021, 02:26

I have to translate the opcode, but I think I get it:
You changed the out instruction to call instruction, followed by 3 addresses
Those addresses point to three subroutine that do something (tomorrow I'll translate what they do) and then they call 93h. But what does the routine @ 93h do?

Van TaylorsEverythingChannel

Champion (415)

17-01-2021, 02:33

93 is also the AY audio output for when it's in the MSX BIOS itself.

Van thegeps

Paragon (1194)

17-01-2021, 09:07

Ok, asked because sg-1000 doesn't have a bios

Van thegeps

Paragon (1194)

17-01-2021, 09:10

So if I take a look on sms bios at 93h I can copy its bios routine that access the SN and copy it in sg-1000 version to be called

Van thegeps

Paragon (1194)

17-01-2021, 10:43

Another question. In your jump table (3rd pic) there are your small routines before call 93h (to pass accordingly parameters, I think) and also after 10 bytes the same routine:

40 Ld b,b
ED B0 Ldir
C3 10 40 Jp 4010h

What is there at 4010h? What are these routines for? These aren't involved in 93h call, I suppose, because after that call there is a ret

Van TaylorsEverythingChannel

Champion (415)

17-01-2021, 17:01

It's just the starting game header itself, and still, 93 is the MSX BIOS call. The MSX BIOS was ported to the SMS. Also, again, 7Fh is for the SG-1000 / SMS SN76489 output audio.

Van thegeps

Paragon (1194)

17-01-2021, 19:12

So the game runs only with cbios installed on sms? Is your cbios that translates musics/sfx by calling 93h?

Van TaylorsEverythingChannel

Champion (415)

17-01-2021, 19:21

Facepalm.
It's only converted to an SMS ROM. Also, I was wondering if you were able to create a game I made, then port it to the MSX. It should be easy, I'll send it on YouTube.
I also converted Earth Attack to Game Gear.

Van thegeps

Paragon (1194)

17-01-2021, 19:32

Ok, then. Msx bios 93h uses msx psg ports, and uses registers as they have to be used with psg management. I think that SN76489 and AY PSG have to be coded differently. So the routine at 93h that you call insode your code, even if it has same address and even if it is a port of msx bios, has to be different from the msx bios one. My question is: where can I find the source of msx bios port for sms?
So I can copy the routine itself in my code and call it as you did in your conversion instead of study the SN76489 and have to write by myself a conversion routine that will steal me a lot of time and provoke a lot of headache?