For those of us who remember LED calculators, the HP 5082-7400 series red “bubble” displays hold a special charm. Available in 3, 4, or 5-digit varieties, these multiplexed 7-segment di… ...

However, since the E Ink display has a low refresh rate, developer Ashtf has devised an interesting solution. He has a smaller OLED display on which anything you type shows up instantly.