Sharp’s Memory LCD, I think. Combination of SRAM cells to hold state in each pixel and improved reflexive backing, otherwise normal LCD, so data input can be stopped without losing contents.
Also to parent comment: backlit LCD without backlight looks like brownish tinted frosted glass. Transreflexives look like calculators and never like a paper. There were high contrast monochrome variant in those Memory LCD products and it looked like half silvered mirror, respectively.
