Tandem Computers Inc yesterday moved its networking software up to Layer 7 of the Open Systems Interconnection model and enhanced communications for its SNAX SNA-compatible and TCP/IP software, and PSX MS-DOS workstations to enable them to use open wide area networking links. OSI Application Services and Transport Services join Tandem’s Distributed Systems Management and are designed to enable users to develop applications without detailed knowledge of the underlying OSI protocols and independently of the communications environment. Tandem also added X25 support to SNAX and to the PSX, and X25, net administration and mail gateway to TCP/IP. OSI/AS starts at $2,475, OSI/TS at $415, X25 for SNAX at $1,650, for PSX at $1,035; all now; and X25 for TCP/IP at $4,000, fourth quarter.