6BX/VIA/ZX81
Jumper Setting

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CMOS Clear   JP7
Normal 2-3 Close (Default)
Clear CMOS 3-4 Close
External Battery 1-2 , 3-4 Close

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CPU External Frequency  JP6 On = Close   Off = Open
ModelRatio JP6
1-2 3-4 5-6 7-8
2.0 x On On On On
2.5 x Off On On On
3.0 x On Off On On
3.5 x Off Off On On
4.0 x On On Off On
4.5 x Off On Off On
5.0 x On Off Off On
5.5 x Off Off Off On
6.0 x On On On Off

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