21020285 D User’s Guide
Appendix B Cables and Connectors
Page B - 2 Introduction
Introduction The SCSI specification allows devic es t o operate with eithe r a single -ended or
a differential SCSI interface. The difference between interfaces is the manner
in which SCSI signals are driven on the cable.
The differential interface uses two lines for each signal (+SIGNAL and -
SIGNAL). A signal is true when +SIGNAL is more positive than -SIGNAL.
This interface provides better noise immunity than the single-ended interface
and so allows a longer cable length to be used.
The single-ended interface uses o ne line for each SCSI signal. All devices on
a single SCSI bus must operate with the same interface.
The RF3880 is available with a 16-bit differential interface, using a 68-pin high
density shielded “P” connector.
Summary This appendix provides the following information:
• Pin-outs of the SCSI connector used for the RF3880 adapter.
• Cable Length allowed for the differential SCSI interface.
• Pinouts of the P1 and P2 VMEbus backplane connectors.
This appendix is most useful for those integrating devices into a system.