Took today off, and so far things are looking good for Vulcan-74.
With the counter section of the new Playfield Generator working, screen clearing is now done in hardware.
This saves the AVR more than 500,000 cycles, and speeds up the system by 60% or more!!
Vulcan-74 can now generate double the number of sprites!
You can never have a large enough breadboard!The new chips added to the board are in the lower right corner.
The lowest row is the X/Y counters that generate the 400x300 addressing to the back buffer.
The row above that is another dedicated megabyte of SRAM that will hold the giant 1024x1024 Playfield Screen.
Currently, only the counters are wired, so the Playfied is just a single color (hard wired to blue for testing).
Setting the single color effectively clears the screen to blue at the start of a new frame.
40MHz on a breadboard? Damn right it can be done!Did I mention that the Playfield Generator is clocked at 40MHz?!
Yes indeed, 40MHz through that mess of new white wiring I have not even cleaned up yet!
It ran at 50MHz as well, but I will be lowering the clock back to 20MHz once the SRAM is connected.
Since the final goal of the Playfield Generator is to send a scrollable 1024x1024 bitmap to the back buffer, I will be lowering the clock back to 20MHz to deal with the propagation from the chained counters to the Playfield SRAM aand then through the 28 bit bus switch. I may try it at 40MHz just to see if a "two in the pipe" mode might work here.
25 huge rotationg sprites bouncing around the screen.Seeing 25 huge (80x80) sprites fly around the screen at 60 frames per second was very impressive!
I can't wait to see the same amount of power with the addition of a 256 color background image scrolling as well.
My poor AVR now has only 1 free pin out of the 32 available, so I may have to start adding the multiplexing hardware.
The 6502 will be even more of a challenge to connect up to the system since it isn't nearly as flexible as an AVR when it comes to IO.
The next step will be to connect the Playfield memory and see if my giant scrollable 1024x1024 bitmap idea works.
From there I will start working on the 6502 part of the logic, as the AVR will have done its job.
The last part of the project will be another 80+ chips to make the 4 voice digital sound generator.
Here is a quick video showing the current system working...
https://www.youtube.com/watch?v=VDsEUw1m-boOk... back to breaking all the rules of bread-boarding, I have another dozen chips to connect!
Cheers!
Radical Brad