Early OIS systems, the 125 and 130, used 8080 microprocessors in the master
unit as well as the peripherals. Newer OIS programs use Z80 opcodes, and
may not run on these systems. Later on, these were replaced with the 125A
and 130A, using Z80 processors. Some systems were available with an optional
extra 64k memory, this required replacing the CPU board with one that contained
a daughter-board with the additional memory.
The OIS-105,115,125A,and 130A are in the large desktop(!?) cabinet you
see on this site. The 140 and 145 are in a cabinet that is about the size
of a dishwasher. The 140 and 145 contain a SMD interface board, for connection
of external disk devices, as no internal disk was supported. The 105 and
115 contained an internal 8-inch hard disk, using SA1000 interface (precursor
to the ST506/412 interface used in PC MFM hard drives). The 125A and 130A
were connected to an external CDC Hawk hard disk (washing machine), with
a whopping 10MB per drive storage space!
Later on, Wang designed the OIS-40 series, a floor-standing machine in a oversize tower style case. These contained 64k memory, a 5 1/4" floppy, and internal MFM hard disk, in various sizes. It also offered 'internal' workstations, where the Z80 board resides in the master unit, and is connected to a 'terminal' by a 15-pin cable. Other internal cards were offered, WISE cards and serial printer cards to name a few. This series consisted of the OIS-40 through OIS-75.
The OIS system was originally the development platform for the WP Systems. The OIS-130 and WPS-30 are the same. The OIS was sold from 1980 to 1990. The OIS Disk Operating System is not Year-2000 compliant.