This is a renaissance of the "Specialist" micro-computer published in the popular "Modelist-Constructor" magazine issue #2, 1987 by A. Volkov.
The original design was used the Soviet i8080A analog - KR580IK80A (KR580VM80A), but this one is based on the Z80A CPU.
Postfix "S" in the project name designates a "simple" design.