A new version of this project is available here
Active termination is required to get newer higher performance drives working on vintage computers. Unfortunately both the Amiga and older Apple computers use a DB25 SCSI connector which makes finding a suitable terminator quite difficult. GTERM25 solves this problem providing a high performance active terminator with a DB25 connector and SCSI diagnostic LEDs.
The board uses a popular SCSI terminator chip from Unitrode/TI. The UC5603 provides termination for 9 lines. Two chips are required to terminate a 8-bit SCSI bus like the one on the Amiga, Apple II and early Macs.
The TERM LED makes sure termination power is present. An additional 7404 inverting buffer drives the other three diagnostic LEDs for SEL, REQ and ACK.
The PCB is shaped to fit into a standard DB25 cable shell.