Arcnet
I doubt there is a TRS-80 owner who hasn't heard about our joint announcement with Datapoint to create an "ARCNET" local network for Model II's, using their protocol and proprietary LSI (Large Scale Integration) chip. Target for availability is the end of the second quarter of calendar year 1982. ARCNET stands for "Attached Resource Computer NETwork". The system will consist of two main components: Applications Processors (work stations which run their own programs locally), and File Processor(s), dedicated to managing the Hard Disk files and requests made on them. A printer can also be attached to thé File Processor for shared use, or of course, any individual Applications Processor can have it's own printer. Communications between the Applications Processor is only via the File Processor. Both Applications Processors and File Processors are Model II TRS-80s, with a board added containing the system
interface (expected to be roughly $400). In addition, there will be a central interconnect box which hooks everything together. Connection is via RG-62/U coaxial cable, and transfer rate is 2.5 million bits per second!
The minimum system will be one File Processor and two Application Processors connected through a lowcost passive (probably about $200) box, capable of adding one more processor. For more processors, a larger active interconnect box (about $2000) can connect eight processors (mixed), or seven processors and one port to connect to a second active box with seven more processors. The theoretical limit to the system is 255 total processors, but the practical limit will probably be around 150. (There will not be a limit on the number of File Processors in a system as there are in some other networking schemes.) An interesting characteristic of the system is that processors can be added or disconnected from the system without disturbing operations in progress.
Let me make it very clear that this joint venture does not mean that Model II's will be running Datapoint software or vice-versa. We will be able to pass ASCII files and requests back and forth between a Datapoint system and a Model II ARCNET, and a user will eventually be able to add a Datapoint File Processor with their 137 megabyte hard disk or 900 line per minute printer to his Model II ARCNET... or even link a Model II ARCNET to a Datapoint ARC network. Our Bisync communications packages will also permit linking a Model II ARCNET to certain other mainframes.
Our intention will be to support our more sophisticated software on ARCNET. We won't "spin up" such things as our current single-disk accounting packages. And, of course, existing Model II's can be easily adapted to work in an ARCNET system.
Advantages of ARCNET
Obviously, the advantages of ARCNET are several. A Model II owner will have an easy and affordable upward path for expansion that will result in more power than a minicomputer system of comparable cost. Multiple workstations will be able to share a common database. The redundancy of having multiple Model II's adds reliability. You could even put a hard drive controller in one of the system Application Processors, so if you have to pull the File Processor for service, you can move the hard disk to the other Model II, and keep going. Unlike Ethernet, ARCNET is based on a proven, reliable technique with more than four years of field operation, it is not sensitive to adding or removing processors during operation, and processors do not have to be attached at precise locations on the cable (and only at those locations).
Well, I've given you about all the information I know right now about ARCNET, so I will ask that you not call your local store, Customer Service, or me for more. There is no more yet. And with that... and since my copy deadline is going to give Federal Air a little more business this month, I'll see you in March! ■
all hardware Model I Lowercase
TRS-80 is a Trademark of Tandy Corp
• DUALCASE— UPPER/lowercase, full time from power-up; NO software; standard typewriter keyboard operation (shift to UPPERCASE); control characters can be displayed; 128 total character set plus full graphics.
• ELECTRONIC SHIFT-LOCK- No extra keys or switches. Simply tap either shift key, UPPERCASE lock, normal shift unlocks.
• DEBOUNCE— If dirty keys are a problem, this is for you.
• BLOCK CURSOR— Easier to locate on a full screen.
• SHORT CASSETTE LEADER
For tape based systems.
• SWITCHABLE- Disable from keyboard.
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