It was released for DMA-capable 8" floppy, extended memory addressing hardware (software controlled 4KiB paging of up to 768 KiB RAM[1]), Motorola 6809 based computers.
On SWTPC machines, UniFLEX also supported a 20 MB, 14" hard drive (OEM'd from Century Data Systems) in 1979.
In 1982 other machines also supported the first widely available 5-1/4" hard disks using the ST506 interface such as the 5 MB BASF 6182 and the removable SyQuest SQ306RD of the same capacity.
This was achieved by writing the kernel and most user space code entirely in assembly language, and by removing a few classic Unix features, such as group permissions for files.
Ports of the Dynacalc spreadsheet and the Stylograph word processor from the FLEX operating system existed but only very few copies were sold.