Adaptec AHA-1540 User Manual - Page 4

Section Three Installation 3.2.4 SCSI Terminator Power Fuse, Fl, controls the terminator power. If another SCSI device is supplying terminator power, then F1 may optionally be removed. No more than 5 SCSI devices should be configured to supply terminator power to a single SCSI bus. Default is Fl installed with the AHA-1540 supplying the terminator power. 3.2.5 SCSI Synchronous Negotiation Jumper set J1, pin pair 1, is the synchronous negotiation enable jumper. This jumper set consists of pin pair 1 in the large block of jumper pins in the upper right hand corner of the printed circuit board. Pin pair 1 is the leftmost pair of pins. J1 3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 pin pair 1 The AHA-1540 will initiate SCSI synchronous negotiation during initialization or after a SCSI reset if this jumper is installed. If the jumper is not installed, the AHA-1540 will still support synchronous SCSI transfers, but the target must initiate the negotiation. Default is jumper removed, synchronous negotiation initiation disabled. 3.3 AT CONFIGURATION 3.3.1 DMA Channel Selection There are three jumper blocks involved in selecting the DMA channel. These are Jl, J6, and J7. The DMA channel selection jumpers consist of pin pairs 7 and 8 located in the large block of jumper pins in the upper right hand corner of the PCB. Pin pair 1 is the left most pair of pins. The DMA channel reported to.the AT during the Return Configuration command is set by these jumpers according to the following table. Default is DMA channel 5. DMA Channel Jumpers Pin Pair DMA 7 8 Channel X X 0 - X 5 X - 6 - - 7 X = Jumper Installed J1 7 8 0 0 0 0 0 0 0 X 0 0 0 0 0 0 0 0 0 0 X 0 0 0 pin pair 1 AHA-1540 3 - 3 adaptec