This big chip is a 8D02D A542K0071. The closest datasheet I could find is of the 8D02E: http://fckuo.sg1003.myweb.hinet.net/spec-pdf/8D02E.pdf Pin 37 on the CSC3100 is connected through a 1.8K resistor to pins 1,3,4,5 and 33 of the 8D02D. For the 8D02E datasheet, these are VCC, RS4, RS3, RS2 and VCC...