@voltagex @LapTop006 … and I thought I suppressed all those memories.

25- and 50-pin are identical signal-wise, the 25-pin variant just removes about half the ground return paths, so avoid if possible and definitely avoid for long runs. Single-ended signaling, 5 to 40MByte/sec. Pretty easy to sort out.

68-pin have 2 different signal variants, differential and low-voltage differential, and are also compatible with single-ended signaling at reduced speed. Here be dragons. Supports up to 16 devices on the bus as opposed to 8 using 50-pin connectors. Wide-differential appeared at the 20MByte/sec generation, LVD became required at 80 MByte/sec generation.

@jpm @voltagex @LapTop006 I remember two node clusters attached to the same storage, changing SCSI initiator ID on one of the hosts. “Good” memories. Also FC-AL.