3 ms·

The ZX80 screen flashed when you pressed a key. Yet they still managed to make games for it by doing cycle accurate delays to account for key processing.

• mzs 5y ago
  indeed: http://www.fruitcake.plus.com/Sinclair/ZX80/FlickerFree/ZX80_DisplayMechanism.htm http://www.fruitcake.plus.com/Sinclair/ZX80/FlickerFree/ZX80...
• Angostura 5y ago
  The ZX81 did the same in "Fast mode". "Slow mode" actually kept the screen refreshed when buttons were pushed - amazing.