The Zenith Z-19 serial terminal is equivalent to the Heathkit H-19 terminal. This is a dumb terminal. It has no local processing functions. It communicates with a minicomputer or mainframe over an RS-232 serial interface. For remote operation, this was often used with a modem. This is late 1970s, early 1980s technology. The monochrome green screen is standard 24 lines x 80 columns, text only, upper/lower case.
Nearby is the TECO editor reference card, and a PDP-8/i reference card.
The classic source code on screen is from www.pdp12.org/ (no affiliation).
This was around $600 new. When I bought this, the serial port didn't work. When I called Zenith, they said I was entitled to on-site support! They sent someone out from the nearest office, about 60 miles away. He found that the baud-rate oscillator was running at the wrong speed. The motherboard was replaced, and it was good to go.
This photo has received quite a few views from various blogs. This photo is on Creative Commons license, and this is how it's supposed to work. I'm encouraged by this sort of behavior to allow more of my stuff to be used on Creative Commons license.
If you're visiting from a blog, welcome, and I appreciate Flickr comments. If you like this photo, you may want to have a look at my other old computer photos in my Computer History set (Link on the right).