It's been nearly four years since the 1.0 release of bB, so it's about time for another. Many things need to be done, but I've gotten over the big hump of letting bB take advantage of special Melody/Harmony features.
We developed the DPC+ bankswitching scheme some time ago. DPC+ is based on DPC, the chip in Pitfall II. DPC+ has evolved a bit since its initial release, and the changes will be documented soon.
For now, I've finally got a functioning DPC+ kernel in bB. Currently, all kernel setup is done with ordinary 6507 assembly language. This will change as this evolves.
Currently, the specs of the kernel essentially combine the best features of the current standard and multisprite kernels, and improve upon both. You get:
- Six sprites (one exclusive, five multiplexed, will be increased to 10)
- All sprites have twice the vertical resolution as other bB kernels
- All sprites can be multicolored
- Asymmetric playfield, any resolution
- Multicolored playfield
- Playfield allows independent resolution control for each 8-pixel column
- Both missiles and ball available and may be any height
- Each sprite allows its REFPx and NUSIZx set independently
- Automatic flickering
The download includes a sample .bas file that shows some of the basic features. Move sprites and other objects around with the left joystick and use the button to switch which objects you move. The right joystick allows you to change the resolution of each playfield column.
I'd like to see is a better demo of the new features, as the included one is quite horrible. If anyone wants to create one, be my guest. Either way, I would like others to play around with the new features and comment. I know there are a few issues, such as no score, you can't yet set playfield colors, and there are some glitches with sprite flickering, but if you find any more, please let me know.
The DPC+ kernel works in a similar fashion to the other kernels. Most of the variables are the same. One main exception is sprite data in DPC+ is stored right-side-up rather than upside-down.
Any binaries will of course work on Harmony, but also included are beta builds of Stella that support the latest DPC+ spec. Included are builds for Windows, OS X and Linux. For OS X, in order to post to this blog, I had to get it under 2MB so I compressed it with 7zip. You can find 7-zip here:
Source for these Stella builds is available at stella.sourceforge.net. These builds will be removed when the next version of Stella is released.