Part II: TRS-80 Network 3 Overview and Demo

Part II of my SepTANDY series: TJBChris' Tandy Education Connection (TEC). In this video, we take a look at the TRS-80 Network 3 controller and software for the TRS-80 Model III and Model 4 computers. I discuss the Network 3 overall, its topology, aspirations, and a provide a high-level look into how it operates. I also demonstrate the Network 3 OS, Network BASIC, and some of the sample programs that came with the Network 3.
Music/SFX (in order):
None. Just me jabbering.
External links:
TRS-80 Microcoputer News Issues: colorcomputerarchive.com/repo...
A Byte Behind Network III web page: abytebehind.com/trs-80-network-3
Vintage Geek's web site: vintagegeek.com/
The CoCo Nation: thecoconation.com/
References:
TRS-80 Microcomputer News - July/August, 1982
TRS-80 Microcomputer News - September, 1982
TRS-80 Microcomputer News - October, 1983
Radio Shack Catalogs: RSC-4 (1981), RSC-5 (1981), RSC-7 (1982), RSC-20 (1989), RSC-21 (1990)
Chapters:
Intro / Follow-up To My Last Video (0:38)
Network 3 Overview (1:40)
A Closer Look At The Controller / How It Works (7:22)
Bootstraping The Network (10:20)
Network 3 Operating System Overview (15:19)
Sample Program: MAILBOX / Running Incompatible Programs (17:47)
BASIC Program Protection (22:01)
Sample Program: MENU generator (26:42)
Simultaneous Request Handling & Capacity Planning (30:05)
Let's Play Some Games! (35:12)
What's Next / Feedback on Your Comments / Outro (37:29)
I do these videos unscripted, so I apologize if the in-the-moment descriptions of things are a bit scattered. If you have any questions/comments about this video, you can find me in any of these fine locations:
The Tandy Discord Server
The CoCo Nation Discord Server
The TRS-80 Color Computer (CoCo) group on Facebook
The CoCo Crew Podcast group on Facebook
On the Vintage Computer Forums (vcfed.org)
The TRS-80 Models I-4/4P Group on Facebook
Tandy / Radio Shack Model II /12 / 16 / 16B / 6000 Owner's Group on Facebook
Twitter (I'm TJBChris there...)
The Level29 BBS (I'm TJBChris there, too.)
Particles BBS (Guess who I am here? Yeah, TJBChris.)
Thanks for watching!

[@VintageGamingMemories]

Glad to have found your channel. New to the TRS-80 world with a recent purchase of a TRS-80 Model III that I've showcased on my channel. You have a great wealth of information here to help me get up to speed. Thanks!

[@TJBChris]

Glad you found my channel, thanks for watching! Enjoy the Model III, it’s an awesome machine. All of the best TRS-80 games run on it, and it has a decent BASIC to boot. I enjoyed checking out your channel (subscribed), looking forward to seeing more of that Model III.

[@BeardedGeezer]

A friend built a multi-user computer system based on a COCO-3 motherboard in a PC case. He made a 12-port serial board that did not use the "bit-blaster" hardware. The system used the OS-9 operating system (UNIX-like) and dumb terminals. The single system was sold to a large nursing home.

[@TJBChris]

OS-9 had great multi-user capabilities - I even did a video about four years ago showcasing OS-9's multi-user capabilities and security layer. It's amazing what a small home computer from 1986 was capable of. The 12-port serial board sounds interesting - I wonder if it was an extension of the single-port RS-232 ports available at the time? Either way, that's a really neat use of OS-9. Thanks for sharing and for watching!

[@derekchristenson5711]

Wow! I've seen videos demoing just two users on one CoCo 3 running OS-9, but 12 would be something to see!

[@larryk731]

I noticed the appropriate wood paneling in the background - well done and extremely age of product appropriate.

[@peterpan408]

Yes a wood panelled room with computers next to each other (no mouse space). Paper on the walls.. Great room.

[@TJBChris]

Thanks for the comment! It’s amazing how many comments I get on the paneling. I never imagined it would have such a following, but it really does look the part. My basement was finished sometime in the 1970s, so this is period-original. Thanks for watching!

[@EdWensell]

Oh the memories! Circa 1990. My high school had one of these setups, and I guess we were bougey as I remember being able to save my work to a disk locally. My final project for the class was a realtime chat program. Used a file on the host system as the communications channel. Basically a user would type a message which was written to the central file. In between user inputs it would read from the central file to display new chat messages from other users. I want to think it worked well up to 5 users or so. Any more users and the disk would get too busy. The chat would continue to work slowly, but any non-chat access was essentially locked out.

[@TJBChris]

Haha I was waiting for someone to mention the word bougie! I was thinking about chat on this system, but like you found, the file-centric nature of Network 3 means it’s very heavy on the IO. Very cool that you made it work, though. That’s impressive. Thanks for watching!

[@ChadDoebelin]

Now I need a TRS-80.

[@TJBChris]

Be careful! TRS-80 computers are like Lay's potato chips: You can't have just one. :)

[@RetroGamingNook]

Yes, they gave you a nice shoutout on CoCo Nation. Great video, this is so informative. We only had the Apple IIe with floppy drives at my high school in the late '80s. My older brother gave me a disk with games that he got from friends back when he was in high school. Evidently, that was his kind of classroom 5 years earlier. By the way, never change that wood paneling.

[@TJBChris]

I’ve had more comments on the wood paneling, it’s hilarious. It really does compliment the machines well…. My school went to Apple IIs, too, and like yours once the IIs came along, each system had disk drives. It’s amazing to me that things like Network 3 were available when disk drives were super expensive to help get the most out of them. Thanks for watching!

[@darrenerickson1288]

Missile Attack, Scarfman, and Meteor Mission 2. Makes me nostalgic!!

[@TJBChris]

So many great games on the Models I/III! It’s amazing what they could do even with the limited graphics on those systems.

[@derekchristenson5711]

That's very interesting to see! My school had a network of Apple IIe's, which allowed loading of a "massive" (for the time) library of educational software (and games!) from a central server with four hard drives, as well as printer sharing. We *might* have had network space to save our work, but I don't remember at this point; we might have had to bring a floppy disk to save our own work.

[@TJBChris]

I've always wondered what Apple's solution for the II line was like, given Apple's ubiquity in education. Thanks for watching!

[@ms_nop]

Tandy thought the classroom computer network would be huge & went all in; like most of what they did, it actually went nowhere. I never saw one of those systems but remember the cringy magazine ads starring Archie & friends! Former owner of an MC-10 then Coco-2 before i bought a used Packard Hell in 1995 to run Slackware Linux, which i continue to use as my primary PC OS to this day! Closest I've come to the setup in this video was at freshman college @ UNLV 1989-90 using ADM3's (or a VT if I was lucky) in the library through an Arrakis concentrator to a MicroVAX 2 (which couldn't handle the load); I could also dial in from my dorm room but used my Freedom 100 because the CoCo-2s 72 column screen didn't work with everything expecting 80 :(

[@TJBChris]

Very cool, I originally started on a CoCo 3. The MC-10 and any of the CoCos were great to learn on in the 80s. My Linux distro of choice was Slack well into the 2000s, but I finally began dabbling in the Ubuntu and Red Hat flavors once my professional life started to take off. The VAX setup you used sounds fun, I’ve never had my chance to have my hands on one. The closest I got was crusty 3270 terminals attached to a S/390 system in the late ‘90s. Thanks for watching!

[@slaquers]

hey cool video, glad I found ya through this one. Subscribed, would love to see a video someday on the TRS-80's implementation of 'UNIX' via Microsoft's Xenix! thanks for the retro vids!

[@TJBChris]

Thanks for watching, I’m glad you enjoy my channel. I do have some bits of XENIX covered in other videos, but nothing comprehensive. Might be worth adding it to the queue. Thanks for the suggestion and the compliments!

[@MnemonicCarrier]

Such beautiful machines.

[@TJBChris]

Thank you! I try my best to keep them looking their best. Thanks for watching!

[@jeopardy60611]

When I was a teenager, I had an idea to create a multi-user bulletin board and chat system with TRS-80 equipment. There was a "multiplexer" device that was advertised in 80-Micro that did networking to a hard drive, probably very similar to this network controller that provides disk access to multiple Model III's. The problem, now that I see it, is that the networking hardware takes up a serial port, so you could not hook up modems to the workstations, so my idea would have never worked. One thing that always fascinated me about the Model I & III is how certain BASIC keywords were vectored out to RAM, and their functionality could be modified, and that is how operations like SAVE, LOAD, OPEN, etc. could be customized for network operation.

[@TJBChris]

Interesting! I am curious about the multiplexer…I’ll have to dig through my 80-Micro issues to see if I can find it. How they did BASIC was pretty neat, and it’s what allowed the cassette-based Level III enhancements for diskless systems, as well as the Network 3 enhancements and regular Disk BASIC. I’ve always thought about experimenting with those keywords, but usually get distracted by something else. 🤣 Thanks for watching!

[@jeopardy60611]

@@TJBChris my understanding is that a lot of things were left out of cassette BASIC because they couldn’t fit in the 12K allowed for the ROM. So, even things like INSTR that had nothing to do with disk access had to be added on by Disk BASIC.

[@TJBChris]

@@jeopardy60611 It wouldn’t surprise me. The fact that the functionality that allowed Network 3 Student Stations to boot over the serial port replaced ROUTE and TIME$ supports that theory. I don’t know for sure, but it sounds realistic to me.

[@jeopardy60611]

@@TJBChris Yeah, TIME$ is a keyword that, by default, vectors out to an L3 error, meaning that it’s an unavailable “Level 3” feature, and the code loaded at boot time modifies it to jump to the routine in RAM to return the time in string form.

[@bokami3445]

30:32 --> Nice handling of multiple requests. Back in High school we has multiple Comadore 4016 PET's hooked up to a dual drive over the IEEE interface. It was common to yell out "Accessing" if you were trying to load/save a program. If two machines tried to access the drive at the same time, the whole setup crashed and required all machines and the dual drive to be powered off and back on. Sorry for the off topic.

[@TJBChris]

I’m glad you liked the segment. Thanks for sharing the info on the PET, I never realized it didn’t like simultaneous requests for shared drives. I definitely consider it on-topic…communications products for machines of this era vary wildly, and it’s fun to learn about them. Thanks for watching!

[@GenXCoder]

I love your collection of TANDYs. I could kick myself for getting rid of mine. I had a TRS-80 Model II, III, IV, and 4P; as well as a Coco2, 1000, and 1000EX over my life. I wish I had kept all of them!

[@TJBChris]

Thanks for the compliments on the collection. Only two have been with me all along (a CoCo 3 and one of my Model 4s), though I had a 1000 SX as a teenager. I've been lucky enough to find some of my more coveted machines (12, 16, 4825 SX) before prices went nuts. The 1000 series can sometimes be had for a fairly reasonable price. They're great machines, and it's fun to explore them now in ways I never had the chance to when they were in their heyday. Thanks for watching!

[@GenXCoder]

@@TJBChris It would be great if you could find a Tandy 5000MC. I've looked but have never found one.

[@TJBChris]

@@GenXCoder I’d love to come across a 5000 MC! It’s one of the few remaining Tandy systems that I’d jump on even though I’m completely out of room for new machines. For a 5000 MC, I’d find a way to make its work.

[@tschak909]

I wish you had shown from a programming perspective how the Network 3 worked.

[@TJBChris]

Thanks for watching! This video was already getting a tad long, so I stuck to the demo for it: I’m hoping to dive into the Network 3 from a deeper technical perspective at some point. Not sure if I’ll make it this month or not, but it’s definitely on the list.

[@cbbcbb6803]

At one point, Tandy Radio Shack had the personal computer industry by the, let's say, hands. What happened?

[@TJBChris]

Sadly, it was a mix of price-cutting and competition across the industry combined with the usual ineptitude that seems to be prevalent in the corporate world that led to Tandy's demise. It's unfortunate, too, because Tandy could have been a bigger player if they could have hung around; they had just started a build-to-order system for their systems, that first appeared in the 1993 catalog (released in August of 1992). You could even customize the nameplates on the system with your name. Of course, 1993 was the year they ended up selling the computer business and R&D to AST, so it didn't last long. If they'd lasted long enough to get that build-to-order offering on the Internet, they could've given Dell a run for their money. Buy online AND be able to haul it to a local Radio Shack for service or pick up accessories locally...it would have been amazing! Thanks for watching!

[@paulstubbs7678]

Rather interesting, I always wondered about networking a TRS-80, they did it - over serial - kind of crazy. It'd be nice to play with such, however me only having a model 1 is a slight problem. A pile if technical stuff would be nice, as opposed to looking at classroom lessons-ware.

[@TJBChris]

I was fascinated with Network 3 as a kid, having played with it. Being able to dive into it now is a dream come true. I do plan to do some more technical work on it beyond this month’s SepTANDY focus, so I hope it’s what you’re looking for. Thanks for watching!

[@deepsleep7822]

I did not know that RS sold a networking product. Were many of them sold? Could non TRS computers be used in the network ?

[@TJBChris]

It sounds like they sold quite a few of these setups. I don’t think they had an installed base anywhere near what Apple pulled off in the late ‘80s with Apple IIs, but my school had a setup, and I’ve heard from a fair number of others who used this. Sadly, Tandy was never big on sharing sales numbers, so I don’t think we have anything concrete. Tandy only ever wrote software for the III and 4, but this is a standard serial port implementation, so as long as the non-Tandy system supported standard serial ports, you could write software that would support that platform. No commercial software for other machines existed, as far as I know. Thanks for watching!

[@melkiorwiseman5234]

That "protected mode" save always puzzled me because I examined protected BAS files on disk using a raw data viewer and saw that the protected program was now just an incomprehensible jumble of characters. I can only guess that "protected" mode would do something to each byte before saving it, such as XORing with Hex FF or rotating each byte before saving. It puzzled me though because I couldn't think of how there could be a foolproof way of detecting a protected BASIC program and not mistaking it for something else. I guess though, if you used the XOR method then you could use the "start of next line" data which BASIC uses, and just look for a foolishly high value in the high byte.

[@TJBChris]

It's something I'd like to dive into, honestly. I noticed the same thing and was hoping I could figure it out. It'd be neat to reverse the protected saves. Thanks for watching!

[@muchosa1]

My school got 4D computers in 1985, my senior year. I don't know which network they used.

[@TJBChris]

Thanks for watching! From the available networks, you would have had your choice of 2 (cassette-based), 3 (serial), or 4 (Corvus Omninet-based). That said, prices started to come down then, so it’s possible to have had standalone disk systems too. I’m not sure if the 4D was ever offered without disk drives, now that I think about it. I’m any configuration, they made great classroom machines.

[@scottbrady419]

That last part you were talking about....I'm thinking saving your High Score on Meteor wouldn't actually work - because it would require writing back out. Right?

[@TJBChris]

Since Network 3 allows student stations to load and save data to and from the host, high scores should stick if the game supports saving them to disk. I don't know if Meteor does or not, though I've found most games don't support any sort of disk interaction. Thanks for watching!

[@idahofur]

I really enjoy it. Early IBM clones had serial networks too. I hope you find a nice large line printer or something that goes along with those trs-80's. I wish I could remember what that is called. Another person years ago connected an ISMAI with 2 terminals. It was doing the same thing. If you was asking the hard drive. Each terminal would wait its turn.

[@TJBChris]

I used to have a 132-column DMP-400 printer...it dimmed the lights when it printed. :) Sadly, I sold it in the '90s with my original Tandy 1000 SX. Though I don't know where I would put it now. IMSAI machines have always been interesting to me, especially since the move Wargames popularized them...very cool machines for sure. Thanks for watching!

[@idahofur]

I had the pleasure of breaking a Trs-80 model 1. Trs-80 coco 2. A trs-80 coco, A free Model III (passed up) and a large metal crate of Model everything non coco you can think of that I passed up. All of this was before the internet except for the crate of stuff. I did not have room for it. @@TJBChris

[@soteful9949]

I used aTRS80 in the 6th grade

[@TJBChris]

Cool! It seems like in those days, it was either Apple IIs or TRS-80s. My school switched, so by the time I came along, there were only a few TRS-80s and many Apple IIs. Thanks for watching!

[@soteful9949]

My teacher would get so pissed when somebody would touch a key and make the floppy drive turn on without a disk in it.@@TJBChris

[@DAVIDGREGORYKERR]

If only the Server had used a ZILOG Z800 or a ZILOG Z8000 you could be running a UNIX Server that could have speeded up the ability to get the file you want much quickly.

[@pikadroo]

You don't need to pander to the LGR crowd with the dumb hash tags. I would have been more interested if this video wasn't algorithm branded.

[@TJBChris]

Thanks, I appreciate the feedback. I really only tag SepTANDY videos, because I know other Tandy folks often search on it. Thanks for watching, and for the feedback!