It may be hard to imagine, but the seeds of what eventually grew to be the Sony Tablet P were planted long before the iPad made tablets cool. The initial idea for a dual-screened clamshell device actually came to fruition shortly after the PDA boom of the late 90s and was first mocked up using a $4 wallet to illustrate the folding concept. Sony’s Takeshi Goto, head of VAIO and mobile products, spoke with Engadget Chinese about the development of the Tablet P from concept to final product, revealing the many alterations made to the design over the years. Designers debated among several screen sizes from 5-inches to 7-inches and evaluated Windows as an operating system on an x86 platform before settling on a two 5.5-inch displays and Android running on an ARM CPU. At one point a prototype more closely resembled the Nintendo DS than the tablet we know today. It’s a design unique from the majority of the tablet field and speaks to Sony’s commitment to innovative design. The full (translated) story and more images can be found at the link below.