The KTM-2 (40 columns) can be used with an RF modulator and any TV set, and its character aspect ratio makes for nicer looking graphics than those provided by the KTM-2/80. The -2/80 is much better for word processing. This sketch below or in PDF format shows how to dual-ize the KTM by adding 2 switches. The switches can be changed while the KTM is in operation, but you may have to use the reset switch.