TNC95 Project Designer: John Koster, W9DDD, w9ddd@tapr.org ---------------------------------------------------------------------------- TNC-95 Alpha Prototype (January 1996) [Image] [Image] TNC-95 alpha board with audio commentary (QuickTime, 1.7Meg, 54secs) ---------------------------------------------------------------------------- General Information TAPR TNC-95 (PSR Issue 57, Winter 1995) It would take a long article to describe the thought and effort that have gone into the design of the TNC-95 as described below. Some of the more important points that have been discussed over the few months, include the need to support: * a low-cost data controller for internal use in the TAPR/AMSAT DSP-93 * future TAPR kits that require data controllers (i.e. PCON, METCON-II, etc.) for those that want a standalone package. * networkers who require a low-cost versatile multi-port network controller that can be used in a variety of situations, but will easily allow for porting of the existing software base. The concept of channel element or communications co-processor could be used in some situations. * a replacement for the TNC-2 bare boards TAPR has been offering since 1991. The process of the design began in July 1994 when a survey was conducted with individuals who had purchased TNC-2 bare boards. This survey was the results of having to make a decision in regards to having more TNC-2 bare boards produced. The PCB house had doubled the price and we really wanted to know if we needed to go to the effort of doing more boards or discontinue the product. The result was interesting -- 80% of the purchasers were only building the data controller section for networking and leaving the rest of the board unpopulated. This seemed to us as a waste of cost to produce a board that more than 50% was not being used by 80% of the people purchasing it. Also, at about the same time, the beta-dsp group had determined that a TNC inside the DSP-93 was going to be required. The decision was made to discontinue the TNC-2 bare board and to start design of what is now called the TNC-95. The TNC-95 is a design that attempts to address a wide variety of needs without requiring "payment" for unused features. The concept currently is that the TNC-95 will be available as a bare board, a core kit, and the additional options that might need to be added later for different functionality. The selection of parts for the unit, should make it easier to find if the builder does not wish to purchase a complete kit from TAPR. Parts procurement for the older TNC-2 bare board was difficult. The core consists of a Z180 MPU, an 85C30 SCC, an EPROM and a SRAM. The EPROM and SRAM may be any size between 32k x 8 and 512k x 8. The core configuration provides two synchronous ports and two asynchronous ports with TTL level interface. No modem is provided on-board. The 85C30 will support a variety of speeds to allow a variety of modems to be supported. Since modems are not standard from area to area, it did not make sense to provide modems on the board. In addition, having the modem as an external device promotes the modular approach that this kits strives for. Many times, the modem and radio are tuned to each other, so this can be a benefit to many. No other components are required to add a second modem channel, except the modem. A second 85C30 can be added. This will allow the addition of 2 more external modems. If high-speed RS232 speeds (TBD) are required, then one of the 85C30 ports can be used for that function. With the above configurations, you can begin to see the potential of this unit. If you are running X1J, THENET, ROSE, or TexNet then no modifications will be required in hardware, since there is enough space for the larger size EPROMS, after code has been ported. In addition, one TNC-95 can replace four TNCs for many that are networking with TNCs. The concept of having the TNC-95 as a channel element for future networking is important. The TNC-95 fills a niche for the 1200-19.2K+ operations and allows other amateur PC boards available to provide higher speed access. No highend limit can be set until the unit is actually finished and tested. We have been in touch with the developers of code for the TNC-2 and will be contacting them when beta-test units are available for them to port code on. Hopefully we will have a wide range of code available around the introduction. The TNC-95 will be in prototyping in January. Timeline after that will depend on how the prototype comes out. A small group of beta-testers has already been selected. Tucson Amateur Packet Radio 8987-309 E. Tanque Verde Rd., #337 Tucson, AZ 85749-9399 Office: 817-383-0000 Fax: 817-566-2544 Internet: tapr@tapr.org