Eric Bylenga

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Home > Model200internet

Interneting on the Tandy 200

Tandy 200 connected to Zimodem module via a DB9 to 25 pin serial adapter

Overview

I discovered a brand new (well super old) world of what the internet was like before HTML. My family did not get online until 1998 or so and my history with the www started with dialup and the very first iterations of DSL by the time I hit my adult years. I browsed early web pages and created a geocities page at some point but the internet existed far before Tim Berners Lee invented HTML. GenX was hitting up BBS servers before I was in diapers. These ASCII and ANSI based realms were full of news, software, chat rooms, art and mail, and they're still alive today.

I've been searching for new uses for my Tandy 100 and 200 and lo and behold, I stumbled on this gem from "What's Ken Making" entitled "Going Online with the Tandy 100". What a treat! Ken goes through all the steps of configuring an ESP8266 devlopment board (available from Amazon for like $15CDN) and connecting it to the Tandy 100 via an RS232 TTL level shifter (also super cheap on Amazon) using the Zimodem project as its gateway to the web.

I was hoping to host this video in Cinepak format for the elderly computers visiting this site, but I never heard back from Ken regarding this. Oh well. I won't go into too many more details, the video is well done. I will say the only difference in my setup is that the Tandy 200 works perfectly well at 1200 baud, but not 2400... I start getting artifacts and weird text at that speed. Ken I recall runs his Model 100 at 600 baud.

Sites that work!

Tandy 200 Connected to Telnet Bible BBS

Many BBS sites out there use ANSI or expect a 80 column display. The 200 and 100 are 40 column machines and support ASCII characters but not alternate character sets. There are a few sites however that work marvelously well on the 200's 16 line display. It's a little more limited on the 100 or 102 with it's 8 lines.

Making it Permanent

I decided to move my project from the breadboard to an actual enclosed case I can carry around with my Tandy 200. I busted out a piece of perf board and soldered some headers to attach the RS232 and ESP8266.

You'll notice the red and black wires extending from the project. As you can see from the above project, the Tandy 200 has its system expansion port right on the back of the computer next to the RS232 port. The two pins closest to RS232 happen to be 5V, while the next two happen to be GND. This provides the perfect method to make this solution perfectly portable and contained when running on batteries.

Breadboard with the headers attached ready for the ESP8266 Completed Circuit

I busted out Tinkercad and made me a case using some old glow in the dark filament I had lying around. Unfortunately I'm not very good at prototyping, I needed to print five versions before I got the measurements just right.

All the prototypes of the case I made before I had a working solution.

And here you are, the final product, with the circuit now protected and more permanent.

In its case!

Once again, connected and ready to internets.

Tandy 200 connected to Zimodem module via a DB9 to 25 pin serial adapter. Another view.

Documents

Tandy 200 TELCOM Reference Manual (PDF)

Downloads

Zimodem Case Bottom (STL)
Zimodem Case Top (STL)

Links

RS232 to TTL adapters with all signals, including DCD.
Tandy Model 200

Last Updated: May 17, 2026