On pixels versus vector: Notably, it all began with yet a different technology. Early computer displays were typically point plotting devices, meaning, these w

On pixels versus vector: Notably, it all began with yet a different technology. Early computer displays were typically point plotting devices, meaning, these were random access displays like vector displays, but had no memory and would plot individual blips on the display. (Moreover, these displays used high-resolution tubes originally manufactured for use in radar displays, employing a dual P7 phosphor that wouldn't only add stability to the image by its sustain/afterglow, but also added iconic trails to any moving objects.) Thus, early games, like Spacewar!, would employ two different modes of graphics: Once, vector like graphics, drawing lines by advancing plotting locations by not more than a screen co-ordinate a step, and on the other hand, painting effects by individual pixels, like the pixel-dust of exploding particles. These displays were also the most limiting factor in game development. As the beam had to be moved at high speeds, displays were serious pieces of hardware, applying high voltages to address the requested plotting locations. In order to prohibit any resulting ringing and blurred images, there was a wait time required in between individual plotting commands. In case of the DEC PDP-1's Type 30 CRT used for the original Spacewar!, these were 50 microseconds, the equivalent of 10 internal CPU instructions. Provided the program had to repaint the screen in reasonable time in order to maintain a stable image and steady frame rates, the time spent in display routines contributed a significant amount to the runtime of the main loop and limited what could be done during a frame.