GPIB ASIC Reference Manual Errata 371430a.pdf GPIB Hardware Guide 370426k.pdf NAT9914 IEEE 488.2 Controller Chip Specification 372013b.pdf NAT9914 Reference Manual 370876a.pdf NAT9914Data Sheet 4gpib705.pdf registers.h test9914.c AN110.pdf cu_usb_serial_4_port.pdf