Since we are pressing on without the pleasure of the company of the OP, I was reading yesterday about how one of the first gaming consoles (or devices anyway) only had 128 bytes of RAM, because it was so expensive. It might have been Pong. So each frame refresh, the entire playing field had to be generated from scratch, because it couldn't be stored in RAM.
The Atari 2600 had no video memory. The video signal out was generated on the fly. This was not just pong, but for every game that ran on this system. I think it generated an interrupt when a scanline needed to be started for output to the TV and then it was up to the CPU to provide the data on the fly.http://en.wikipedia.org/wiki/Atari_2600
A lot of vector games worked this way too. For vector monitors this makes total sense because the main program has control of the electron gun and doesn't even have the constraints of timing, except how many inches of line it can draw between refresh cycles.