Earlier version of the cable (V1). The I/O on pin 4 is harder to drive than pins 1,2,3 so the pull up resistors were used to try and correct the voltage levels, but even then it was still iffy.
Vectrex A Vectrex B
1 |--------------------------| 4
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>
< 600 Ohm Resistor
>
<
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8 |--------------------------| 8
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>
< 600 Ohm Resistor
>
<
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4 |--------------------------| 3
2 |--------------------------| 1
3 |--------------------------| 2