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Old 23 February 2009, 23:51   #41
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Join Date: Jan 2004
Location: Oxford
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Originally Posted by BoingBall View Post
I also helped porting FPGA64 (C64)
It shouldn't have taken long, it was a nice well presented open source project (Unlike Amstrad which is written entirely in AHDL) and the MiniMig I/O wrappers are reasonably well written and documented. Getting stuff on the screen and I/O control should have only taken a few hours (most of that reading + DCM configuring).

Loading the ROMs from SD card through the PIC to SRAM is the only hard bit. MiniMig uses a special "built in" bootloader ROM written in 68000 to move the Kickstart from the SD card using the floppy disk interface to the PIC over to SRAM before rebooting.

Originally Posted by BoingBall View Post
We have a well working VIC20 core too. Additional some other little things like MiniPong etc.
Porting cores is very very easy once you've learned the interface wrappers (VGA, Keyboard, Sound, Joysticks).

When I first got my MiniMig board several years ago I had a go at porting C64, Amstrad, Spectrum, MSX2, Vic20 and more recently Atari ST.

The bootloader was the hard bit. It required re-writing some/all of the PIC to come up with a new way to program the FPGA and SRAM on power up. I got bored by this point and put it down.... never to pick it up again

I'd be curious to know if anyone wrote a new PIC/bootloader?

Last edited by alexh; 24 February 2009 at 00:01.
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