The company I work for is beginning to incorporate LCD screens onto its devices, but not touch screens. These machines will be used in dirty, dangerous environments, so touch screens are not practical.
For cost and space reasons, one particular device can only have a max of 4 buttons. However, they want the user to be able to store 8 different settings in the memory. They're proposing something like this (colors and fonts changed for anonymity).
Each button would hold two memories, and you would switch between the two by pushing the button twice. You tell which memory you're in by which side the light is on. In the picture, you would be in Memory 2, because the light is on beside the 2.
My gut reaction is that the extra button presses and dual settings on each button make this a bad UI design. But does anyone have any research to back this up or refute this? Are there studies on this sort of behavior? Antecdotal findings? Or can this only be solved through testing? Thanks.