HECnet_
DECnet Phase IV • Area 31 • 3 active nodes
What Is DECnet?
DECnet is Digital Equipment Corporation's proprietary network protocol suite, first introduced in 1975 and reaching its mature form as Phase IV in 1982. Unlike the TCP/IP stack that dominates networking today, DECnet was a fully integrated system designed specifically to connect DEC minicomputers and workstations. It provided terminal access (SET HOST), file transfer (NFT / COPY), mail, and remote job submission — all with a clean, uniform interface regardless of whether the remote system ran RSX-11M, VMS, TOPS-20, or ULTRIX.
DECnet Phase IV uses a two-level addressing scheme: an area number and a node number, written as area.node (e.g., 31.130). Areas 1-63 are valid, with each area supporting up to 1023 nodes. Routing is handled by designated Level 1 routers within each area and Level 2 routers that interconnect areas. The protocol runs over Ethernet and, with modern bridges like PyDECnet, over TCP/IP tunnels as well.
What Is HECnet?
HECnet (Hobbyist Ethernet Connect network) is a global DECnet Phase IV network for enthusiasts, founded and maintained by Johnny Billquist. It connects hundreds of vintage DEC systems and emulators worldwide, allowing hobbyists running OpenVMS, RSX-11M-PLUS, TOPS-20, and other DEC operating systems to communicate with each other exactly as they would have on a corporate DECnet in the 1980s and 1990s. The backbone is carried over the modern internet using DECnet-over-IP tunneling via PyDECnet and Multinet bridges.
HECnet is a volunteer-run community. To join, contact Johnny Billquist at bqt@softjar.se to be assigned an area and node number. There is also a mailing list for HECnet participants where routing changes and new nodes are announced.
Our Nodes
LARRY • 31.130
RSX-11M-PLUS V4.6 BL87 on PiDP-11/70 (SIMH on Raspberry Pi). Connected to HECnet via BQTCP Multinet TCP relay through PyDECnet router CURLYR.
CURLY • 31.132
OpenVMS V7.3 on VAX 8600 (SIMH under WSL). Connected via Ethernet TAP interface bridged through PyDECnet router CURLYR.
CURLYR • 31.134
PyDECnet Level 1 router. Bridges LARRY and CURLY onto the HECnet backbone. Connects upstream to PYRTR (31.3), a PyDECnet Level 2 backbone router.
Network Architecture
Our local DECnet area (31) is structured as follows:
RSX-11M-PLUS
PyDECnet L1 Router
HECnet L2 Backbone
CURLY (31.132) connects to CURLYR via a TAP interface, appearing as a directly attached Ethernet neighbor. LARRY uses BQTCP's Multinet driver to reach CURLYR over a TCP tunnel, since the PiDP-11 does not have native Ethernet DECnet support.
Reachable Nodes with Guest Access
From any of our nodes, you can reach these systems on HECnet using SET HOST nodename (on VMS) or NCP SET HOST nodename (on RSX):
| Node | Address | System | OS | Access |
|---|---|---|---|---|
| MIM | 1.13 | PDP-11/74 (real hardware) | RSX-11M-PLUS | GUEST / GUEST |
| CTAKAH | 62.637 | PDP-11/94 (real hardware) | RSX-11M-PLUS | GUEST (no password) |
| CHIMPY | 8.400 | AlphaServer | OpenVMS V8.3 | has TETRIS |
| BIGSYS | 62.3 | PDP-11/83 (real hardware) | RSX-11M-PLUS | GUEST (no password) |
MIM (1.13) is Johnny Billquist's own system and the traditional first stop for new HECnet visitors. It runs RSX-11M-PLUS on a real PDP-11/74 and has a wealth of documentation and programs available to guest users.
How to Join HECnet
HECnet is open to anyone running a DEC operating system or emulator. To connect:
- Contact Johnny Billquist at bqt@softjar.se to request a node address assignment
- Subscribe to the HECnet mailing list for announcements and routing updates
- Set up PyDECnet, Multinet, or a similar DECnet-over-IP bridge on your system
- For VMS systems, DECnet Phase IV is included with OpenVMS and requires only network configuration
- For RSX-11M systems, BQTCP provides a Multinet driver that supports DECnet over TCP