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Mega Man 2600 demo game (binary)


djmips

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Could someone please answer my question?

 

Try right clicking the link and selecting 'Save Target As'.

 

-Trebor

 

 

It worked! But now I've got another question: how do you shoot?

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Could someone please answer my question?

 

Try right clicking the link and selecting 'Save Target As'.

 

-Trebor

 

 

It worked! But now I've got another question: how do you shoot?

 

ah... yes it's a bit weird. You pull down on the joystick to shoot.

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ah... yes it's a bit weird. You pull down on the joystick to shoot.

Do you plan to make the button fire and moving the joystick up jump?

 

No, because I think that jumping is important enough that the timing/control just wouldn't work with that scheme. It does make shooting awkward but shooting doesn't have quite the timing issues. I would consider releasing a version for the Genesis controller because it 'just works' as a two button controller for the 2600.

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I'm not knocking the demo or anything. The music is really great, in particular. But I'm a little curious as to why this demo required 32K ROM and the SARA chip. Even when I count fixed point variable pairs for the player and enemies (max 8 with MegaMan and two blocks, if the blocks movement is fractional), a couple of frame pointers, some bits for direction and state and a few sound pointers I still come up short of the 26 addresses available in an unmodified batari memory map. The ROM usage seems a little unusual to me too, given that there are only 5 distinct playfields and a handful of monotone spritesets. Was the majority of of the ROM space used up on the title screen somehow?

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I'm not knocking the demo or anything. The music is really great, in particular. But I'm a little curious as to why this demo required 32K ROM and the SARA chip. Even when I count fixed point variable pairs for the player and enemies (max 8 with MegaMan and two blocks, if the blocks movement is fractional), a couple of frame pointers, some bits for direction and state and a few sound pointers I still come up short of the 26 addresses available in an unmodified batari memory map. The ROM usage seems a little unusual to me too, given that there are only 5 distinct playfields and a handful of monotone spritesets. Was the majority of of the ROM space used up on the title screen somehow?

 

Yes on the ROM size. The project was done under a very tight deadline and I didn't want to concern myself with optimizing for size and I specified 32K plus 256 bytes of memory from the start. One of the reasons was that I had more ambition than the final product shows, so some features had to be cut. It did turn out that the final ROM is using a bit over 16K however (actually 14K + 2K for SARA) so I did need the 32K (the next size). Note that the SARA chip memory maps eats away 256 bytes per 4K. One of the biggest costs in the ROM is for the frames of animation for Mega Man and Elec Man which eats away memory at a terrific rate (compared to code).

 

The bBasic code adds a bit to code bloat. I do overlap variables from game to the Boss fight to save RAM. You also might be surprised at the amount of variables that are needed for Mega Man for instance for the extra touches like his eye blinks, the timer for how long he stays invincible after being hit etc. Even so, it may be possible that it could have been crammed even into the normal 128 bytes, especially if I wasn't using bBasic but it just would have been much more time consuming to make.

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One of the biggest costs in the ROM is for the frames of animation for Mega Man and Elec Man which eats away memory at a terrific rate (compared to code).

 

But isn't all of the sprite data included in the same bank as the batari kernel? In other words, as far as I know the total sprite data for P0 and P1 cannot exceed the size of a single bank. If this isn't the case, it might be useful to know how you worked around this limitation.

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One of the biggest costs in the ROM is for the frames of animation for Mega Man and Elec Man which eats away memory at a terrific rate (compared to code).

 

But isn't all of the sprite data included in the same bank as the batari kernel? In other words, as far as I know the total sprite data for P0 and P1 cannot exceed the size of a single bank. If this isn't the case, it might be useful to know how you worked around this limitation.

A common solution is for multiple banks to have kernel copies. I.e., bank 1 has the kernel and Mega Man & enemy #1 sprite data. bank 2 has the kernel and Mega Man and Elec Man sprite data.

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I don't know. Maybe if I had some help getting some more levels made and I'd have to see if Albert was interested.

im sure a lot of people would jump into that and help. if or when you do add more things you should make the black and white switch pause the game, that would be a cool feature

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