Pksmart
From Just Solve the File Format Problem
Pksmart is a menu-driven compression utility for DOS. It is credited to "Puchkov Sergey and Alex", also given as "PSV & Alex".
It does executable compression of EXE files (to EXE), and COM files (converting them to EXE). It also compresses non-executable files to its native .PKS format.
It is not related to PKZIP, or any other PKWARE product.
Identification
(Based on v1.0b.)
Compressed EXE files have bytes 'P' 'K' 'S' 0x01
at offset 28. Better identification could be done using the bytes starting at offset 36, though some bytes have to be ignored.
PKS files start with bytes 'P' 'K' 'S' 0x01
.