RS-232 to Video – The Easy Way

With the trusty ZX81/TS1000 destined for a place in a dusty closet, here’s a way to put it to use in the event you need a video output from a device having a RS232 serial port. Two examples are the HP41C calculator/computer and Tandy’s new Model 100 portable computer.

First, to give credit; Charlie Welch, W5TLU, here in Las Cruces is the creator of this idea. He gave me his notes and software and left me with the task of getting it written up. He also gave me a demo of it working with my new Model 100 portable computer and I’m anxious to build one myself.

This article revolves around the Byte Back RS232 interface ( $60/kit). If you would rather homebrew your own, see the excellent article in Nov/Dec ’82 Sync, “Your Timex/Sinclair Can Become a Terminal” by V.B. Rice. We will leave the hardware up to you, this article details the software necessary to get the Sinclair to act as a dumb display device. Sounds a bit strange, but where else can you go from RS232 to video for $100? You can, of course, use either the standard TV output of the Sinclair or modify it for direct video output for use with a video monitor. Remember, the mod only takes two wires!