Specifications

DocSTAR Level 2 Service Training Workbook Page 5
This is a passive terminator circuit:
Figure 1.7: Passive Terminator Circuit
This is an active terminator circuit:
Figure 1.8: Active Terminator Circuit
The final component that must be in place for the SCSI devices to communicate with the
PC is the Advanced SCSI Programming Interface (ASPI) Software. The ASPI software,
also known as the ASPI Layer, is the software that is responsible for all communications
between the PC operating system and the SCSI host adapter. The ASPI layer acts as an
interpreter on behalf of the SCSI host adapter and the PC operating system, as shown in
Figure 1.9. Commands are passed from the operating system to the ASPI layer. The
commands are then converted to command strings that the SCSI host adapter can
understand. The result of those commands is then passed back through the ASPI layer to
the operating system. Windows 9x has a built-in default ASPI layer that loads
automatically when Windows detects a SCSI host adapter. DocSTAR systems should
be upgraded to the most current Adaptec ASPI layer, provided by BitWise Designs,
for optimum performance.
Figure 1.9: ASPI Layer Diagram
Reference
For more information please refer to the following DocSTAR Service Bulletins:
5031 Adaptec SCSI Adapter AHA-1520A
5037 Multifunction 5¼” Phase Change Drive
5039 PD Drive SCSI Settings
5053 5.25” 2.6GB Drive Settings
5054 3.5” MO Drive Changes
5055 SCSI Controllers
5061 SCSI Controller 2940
5065 3.5” MO Drive Changes
5071 T5 2.6 Gig Optical Drive
5075 Multiple SCSI Controllers
5077 T5 STAR Drive Settings