This is the project version that builds the FPGA bitstream for the Tang Nano 20K version of the A2FPGA Apple II card.
The A2N20v1 version only supports Apple II and //e models. The card will not work correctly in a IIgs. The v1 card uses a 64-pin "a2bridge" CPLD to interface and level-shift the Apple II bus that unfortunately does not capture the Apple IIgs M2SEL and M2B0 signals necessary for correctly capturing IIgs memory addresses on the bus.
It supports all graphics modes on all Apple II models, although software written for //e double-hires will not usually run on a II, nor will IIgs software run on a II or //e. However, the soft switches and display modes are supported on all models for software you write yourself.
To update the bitstream on the A2N20v1, the most convenient way is to use OpenFPGALoader
Mac users with Homebrew can just type brew install openfpgaloader in the Terminal to install it
Use OpenFPGALoader to program the Tang Nano 20K board via USB with the a2n20v1.fs bistream file and run openfpgaloader -b tangnano20k -f a2n20v1.fs
The project can also be opened and built with the Gowin IDE, either educational
or commercial editions. Use the a2n20v1.gprj file in this folder.
Note: When using the Gowin IDE, do not add or remove files from the project or it will turn the relative file paths into absolute file paths.