Technologic Systems products use two types of PC104 connectors: 1.) the standard PC/104 connector and 2.) the PC/104 stack-thru connector. The standard connector is for any SBC used by itself or at the bottom of a PC/104 stack. The standard connector is provided on all of our PC/104 SBCs by default. The optional stack-thru connector is for clients who wish to use a Technologic Systems SBC in conjunction with their PC/104 motherboard. In this case, the Technologic Systems SBC will be mounted above the client board and will require a PC/104 stack-thru connector. PC/104 peripherals (daughter-boards) always have a stack-thru connector, because they must be mounted above the PC/104 SBC. Below you will find pictures of the two PC/104 connectors and an example of a PC/104 stack.
The PC/104 connector consists of two parts, the 64 pin connector and the 40 pin connector. Many PC/104 peripherals only utilize the 64 pin connector. If none of the peripherals you plan to use have a 40 pin connector, your SBC does not need the 40 pin connector.