Make a chargen file (character generator ROM) from an 8x8 text file with 512 characters. I.e. you can edit the fonts easily in a text editor e.g. Notepad or Nano. This system is for Linux, but propably works in macOS or Windows 10 with an Ubuntu app from Store. You can use the chargen file in a C64 or X16 emulator.

\ = 0
@ = 1
Empty lines, lines with only space characters, and lines starting with # are skipped.

./build.sh

./build.sh zx81.txt

./bin2txt.sh

./bin2txt.sh zx81.bin

x16emu -bas petscii.bas

x16emu -rtc -bas clock.bas

I don't own the copyright of these fonts, but the Sinclair ZX81 and ZX Spectrum fonts are OK to distribute because Amstrad Ltd has kindly given their permission to do so. They are e.g. included in ROMs with the GPL license. The IBM font is public domain, see https://github.com/dhepper/font8x8. The CP437 font (also by IBM) is probably public domain and was found on https://github.com/emaste/fontstuff/tree/master/syscons-fonts.

The Commodore 64 PETSCII font is a more tricky case, see http://c65gs.blogspot.com/2015/04/is-c64-font-protected-by-copyright.html. I could remove the PETSCII font in chargen.txt if e.g. Cloanto complains. One argument that the PETSCII font might be public domain is that these pictures of it are in public domain and the text file can be reconstructed from the pictures. Here is a PETSCII Reference which also contains pictures of the font.

The license of this repository is only valid for the code and documentation - not the fonts.