What is the potential of today's technology?

Ok, so for a long time now Ive been wondering this question and never truly asked about it. But, I would like to compare modern day technology to that of the past. For example and I might be totally off on this but: So the TV was 'inventible' around the 1920's. Who's to say we couldn't do it before? Perhaps even 1890. What's to say you could'nt just create a 37" HDTV at 1080p with the 1920's current resources? I mean sure, knowledge is a virtue to even take a step there but... if we wanted to (i.e. some dude from the future provides blueprints for some of 21st Century's technologies.) Could we build it? If anyone has actual data that can provide with a better understanding of these possibilities, that'd be great. Otherwise, I welcome any and all relevant thoughts.