When sourcing ISA slot motherboards, primarily used for legacy industrial equipment, you must verify the chipset compatibility (e.g., Intel 845, G41, or specialized industrial chipsets) to ensure it supports the ISA bridge. Key specs include the number of physical ISA slots, CPU socket type (LGA 775, Socket 370, etc.), and RAM type (DDR/DDR2/DDR3). Ensure the board features solid capacitors for 24/7 operational stability and check for onboard serial (COM) and parallel (LPT) ports, which are often required alongside ISA cards.