Virtual designed operating system for EC 1025 (not to be confused with DOS for IBM PC compatible).
The minimum RAM size requirement was 64 KiB.
The core of the operating system and compiler (Systran, Pascal, C) was programmed by Václav Trojan.
Compared to its predecessor (the DOS-I system, created in the GDR and the DOS-II developed in the USSR), DOS-III was expanded with the functions of more comfortable OS/VS systems, operationally (i.e.
however, it was compatible with DOS/VS, allowing earlier applications to run without having to be reworked.