These fonts were (it seems) originally developed for use with Czech and other Eastern European languages, and then extended for more general use. They don't, in fact, cover the entire T1 encoding, but they come pretty close. The fonts are distributed as MetaFont source.

Both font families come in both upright and "slanted" shape, and in both medium and bold weight (an interesting choice, given that the "medium" is already pretty heavy).

See also blacklettert1.

The authors are Vladislav Kurz and Daniel Taupin.