Darrin wrote:
Nice work. So, is the standard aCube Minimig fitted with 10ns SRAM?
Unfortunately no, it has 55ns SRAM.
I think it may be possible to optimize the DMAs to make them run on a 16 or 12 MHz bus :
One cycle out of 4 is given to the main Z80 and one cycle out of 8 to the audio Z80. But, these two Z80 use 8 bits out of the 16 bits read. With a simple caching of the second byte fetched, almost 50% of the Z80 fetch cycles can be saved.
The FPGA implementation can display 128 sprites per scanline, which will never happen (even the NeoGeo displays a maximum of 96 sprites per scanline). A lot of DMA slots are wasted here. I think I might be able to set the limit to 32 or 48 sprites.
I must admit to liking 1943. The Amiga version of 1943 runs well, but a pure arcade version would be very nice.
Honestly, I was pretty disapointed by the Amiga version.
The FPGA version seems to be smoother than the arcade : there is no slow down when a lot of sprites are on the screen. This is because I made the main Z80 working at 24 MHz instead of 6 MHz. Just the instruction fetches are limited to 6 MHz. The animation is anyway synchronized with the VBLANK interrupt so the extra speedup on the Z80 does not turn the game into an implayable one.
Now, I am working on a scale2x algorithm to improve the graphics.
Regards,
Frederic
