ZUMA168 After turning off memory protect, the correct value could be entered. The fourth article of the series presented modifications to use a companion RCA 1861 “Pixie†video generator IC (CDP1861). The Pixie required a 1.76 MHz clock, and since that was an uncommon crystal frequency, usually a readily available 3.579545 MHz colorburst crystal was instead used in a separate oscillator circuit with a divide-by-two circuit to drive the clock inputs of both the microprocessor and Pixie.|{3|4|5|6|7|8|9|10|Three|Four|Five|Six|Seven|Eight|Nine|Ten} Ways to Guard Against Slot