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Independent Evaluations of Networking Products and Tools |
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The Fastest Network Alive TCNS isn’t exactly a network standard. It also isn’t exactly slow.
If you have fast workstations and a fast file server, you want a fast network. Even 16 megabits per second may be too slow if your applications are data-intensive. TCNS, from Thomas Conrad, operates at 100 megabits per second and doesn't cost a lot more than Token Ring. TCNS gives you all the advantages of FDDI without FDDI's high price tag. I found NetWare, LAN Manager, POWERLan, LANtastic, and other ARCNET-compatible network operating systems work well with TCNS. The only catch is that you have to use fast computers to realize performance gains with TCNS.
You can use the same shielded twisted pair (IBM Type 1) or coax (RG62A/U) cabling already in place for Token Ring or ARCNET, or you can install 62.5-micron fiber optic cable. You can mix and match cable types by using a TCNS Smart Hub with different connectors. You wire a TCNS network in a distributed star fashion, just as you would with ARCNET or Token Ring. TCNS adapters and hubs use ST connectors for fiber optic cable, BNC connectors for coax, and DB-9 connectors for STP.
Imagine ARCNET running at 100 mbps and you have a good picture of TCNS. A TCNS network adapter is register-compatible with an ARCNET adapter, which lets TCNS use industry-standard ARCNET software drivers. Thomas Conrad also supplies "Accelerated Drivers" for an even greater performance boost. TCNS workstations uses the same reconfiguration process as ARCNET when they enter or leave the network. Over the LAN cable, though, TCNS uses FDDI's 4B/5B encoding scheme to send and receive the ARCNET packets. It's the best of both worlds.
TCNS consists of network adapters with STP, coax, or fiber optic connectors, one or more Smart Hubs, and software drivers. The adapters come in 16- and 32-bit, ISA- and EISA-bus varieties. You can put up to 255 TCNS workstations on a single LAN segment, and you can span significant distances - 2,950 feet (hub to workstation) with fiber optic cable, 492 feet with STP cable, and 338 feet with RG62A/U coax cable.
A TCNS adapter contains an Advanced Micro Devices (AMD) TAXI chipset. Thomas Conrad developed the firmware and microcode for TCNS by layering its own chip designs on top of TAXI. The 4B/5B encoding scheme lets TCNS transmit 4 data bits as 5 signal bits, making it 80% efficient. By comparison, the Manchester and Differential Manchester schemes of Ethernet and Token Ring are only 50% efficient.
TCNS cards, like most IBM Token Ring cards, use 16 kilobytes of upper memory. I was easily able to configure 386MAX to load DOS and my TSRs in upper memory around the TCNS card. The on-board RAM is zero-wait-state.
How fast is TCNS? I tested a set of TCNS cards on my LAN at home. With a 33 Mhz 80486 EISA-bus file server running NetWare 3.11, and with a set of workstations that include 33 Mhz 80386 computers as well as an old IBM PC, I found the workstations could read and write files to/from the server about as fast as they could read and write files to a workstation RAM disk. The BYTE LAN Benchmarks measured TCNS message-passing speed at 700 kilobytes/second. That's quick. TCNS definitely eliminates the network cables and network adapters as a bottleneck on your LAN.
If you use an old, slow XT on a LAN, you don't need TCNS. I noticed that TCNS didn't help my original-issue, 5-slot IBM PC perform any better than Ethernet, Token Ring, or plain ARCNET. In this case, the workstation is the bottleneck and no amount of high-tech networking would help. But fast workstations are different. An 80386 workstation will operate faster than some networks can deliver the data. TCNS eliminates the network bottleneck for such workstations.
Datapoint announced a 20 mbps ARCNET-Plus product almost two years ago, but has yet to ship the product. The fiber optic version of TCNS has been available for about a year, but the STP and coax TCNS cards and hubs are new. $745 for a 100 mbps, 16-bit copper-based network adapter -- in a fast workstation or server, of course -- is a reasonable price to pay for performance.
THE FACTS: TCNS -- Thomas Conrad Network System
Shielded twisted pair, coax, or fiber optic network adapters, 16 or 32 bit, ISA or EISA bus -- $745 to $1,595 TCNS "Smart Hubs" -- STP, coax, fiber, or a combination -- $1,995 to $2,495 Requirements: NetWare, LAN Manager, LANTastic, or any ARCNET-compatible network operating system
Thomas Conrad 1908-R Kramer Lane Austin, Texas 78758 (800) 332-8683 (512) 836-1935 FAX: (512) 836-2840
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