Microtek ScanMaker IIG User Manual page 243

If you have an ASPI Card
Appendix G
Cabling
The following scenarios are provided to show how to connect your scanner to
the computer and the other components you may have in your system while
using an Adaptec AVA-1502E card or Adaptec compatible ASPI card.
Microtek scanners are not internally terminated. Always use short cables no
Note
longer than 4 feet for connection; longer cables can cause SCSI-related
problems.
Connecting a Microtek scanner to a PC. There are no other SCSI
Case 1
peripherals.
Note: In the above installation, you may also need to use a 50-50 pin
peripheral cable and a terminator on the scanner. Terminators are not
provided with Microtek scanners.
PC SCSI cable
scanner