Previously embedded below was a short video showing me testing one of the Collins radios we manufacture. The product has since been considerably upgraded and seeing as more recent video now exists, I've deleted the link below and moved the updated version to a newer post.
The top display is the ACTIVE setting whilst the lower display shows the STANDBY.
The standby setting is swapped to become the active one by momentarily flicking the right-hand transfer switch (named XFR). Switching to the MEM function (memory) allows you to cycle through up to ten preset frequencies.
The smaller knob on the dual concentric rotary encoder controls the decimal numbers, and the larger one handles the whole numbers.
The example shown in this video is running as a NAV radio (hence the .05 steps) although by making a simple alteration to its software it will then function a COM radio, which steps like so: 0 - 2 - 5 - 7 and back to 0.
The software can also convert it into either an ADF or a Transponder, although of course they have no standby function, and the decimal point on the ADF is in a different place.