"Now we have a digital counter in sync with the video signal." This principle was maintained for many years until the homecomputer era came to an end. The CPU

"Now we have a digital counter in sync with the video signal." This principle was maintained for many years until the homecomputer era came to an end. The CPU (and all the auxilliary chips) used to run in lock-step with the video signal. The whole architecture of many games from that time was built around the position of the electron beam on the screen. We exploited that to switch video modes in the middle of the screen (text/graphics split screen), draw in the overscan area (raster bars) or multiply the number of hardware sprites by quickly alternating different sets at certain scanlines. The V-sync pause was a welcome rest and spent to calculate the game logic. Another interesting consequence of this was that US homecomputer models ran at faster clock speeds than the Euro models because of the higher refresh rate of NTSC. With clock speeds in the single digit megahertz range the 60/50 ratio was not negligible. In Europe we did hw mods to add a switch that made the computer run at NTSC speed even if that meant no video. You had the choice: a fast computer with no output or a slow one with video.