Heathkit H-19

The H-19 was a great terminal. It was a truly great product. Great functionality, solid and reliable, and economical. And Heathkit and Zenith sold a ton of them, tens of thousands (might have even gotten up over 100,000). The H-89 (and all of its' variants) was just an H-19 with a single board Z-80 computer stuffed into the same cabinet. There were actually two major variants of the H-19, the original one and the later one that was re-engineered to meet FCC Class "B" RFI reduction approval. They are functionally the same, and the overall circuitry and firmware are more or less the same, but there are some changes internally (fairly major, actually). You can tell the later one because there is a circuit card on the CRT socket; on the early one, the CRT socket was just a CRT socket with wires running to the deflection board assembly.