To use some of the most attractive prompts in the Bash Prompt package, you need to get and install fonts that support the character sets expected by the prompts. These are "VGA Fonts," which support different character sets than regular Xterm fonts. Standard Xterm fonts support an extended alphabet, including a lot of letters with accents. In VGA fonts, this material is replaced by graphical characters - blocks, dots, lines. I asked for an explanation of this difference, and SÚrgio Vale e Pace (firstname.lastname@example.org) wrote me:
I love computer history so here goes:
When IBM designed the first PC they needed some character codes to use, so they got the ASCII character table (128 numbers, letters, and some punctuation) and to fill a byte addressed table they added 128 more characters. Since the PC was designed to be a home computer, they fill the remaining 128 characters with dots, lines, points, etc, to be able to do borders, and grayscale effects (remember that we are talking about 2 color graphics).
Time passes, PCs become a standard, IBM creates more powerful systems and the VGA standard is born, along with 256 colour graphics, and IBM continues to include their IBM-ASCII characters table.
More time passes, IBM has lost their leadership in the PC market, and the OS authors dicover that there are other languages in the world that use non-english characters, so they add international alphabet support in their systems. Since we now have bright and colorful screens, we can trash the dots, lines, etc. and use their space for accented characters and some greek letters, which you'll see in Linux.