TSX-32

TSX-32 has been a general purpose 32-bit multi-user multitasking operating system for x86 architecture platform, with a command line user interface. It is compatible with some 16-bit DOS applications and supports file systems FAT16 and FAT32. It was developed by S&H Computer Systems, and has been available since 1989.
DEC-oriented columnist Kevin G. Barkes noted that TSX-32 is "not a port of the PDP-11 TSX-Plus" and that it runs
well on 386, 486 and Pentium-based systems. He reported a limitation: since it supports the MS/DOS (FAT) file system, filenames are DOS's 8+3.
TSX-Plus.
An earlier non-DEC operating system, also from S&H, was named TSX-Plus. Released in 1980, TSX-Plus was the successor to TSX, released in 1976.
The strength of TSX-Plus is to simultaneously provide to multiple users the services of DEC's single-user RT-11. Depending on which PDP-11 model and the amount of memory, the system could support a minimum of 12 users (14-18 users on a 2Mb 11/73, depending on workload). A productiveity feature called "virtual lines" "allows a single user to control several tasks from a single terminal."
History.
S&H wrote the original TSX because "Spending $25K on a computer that could only support one user bugged" (founder Harry Sanders); the outcome was the initial four-user TSX in 1976.
For TSX-32, they said in an interview, "We started with a clean sheet of paper" rather than starting with a "port."
As of 2021, it appears to be defunct.
VAX.
The company's product line was ported/expanded for the VAX line.