the same board location as the legacy PC/104 ISA connector. In addition to PCI Express, the specifications also defines pins on the connector for additional modern computer buses, such as USB, SATA, and LPC. The PCI/104-Express specification currently defines two possible pinouts for the PCIe connector: Type 1 offers four x1 PCI Express links, two USB 2.0 ports, and one x16 PCIe link. Type 2 offers four x1 PCI Express links, two USB 2.0 ports, two PCIe x4 links, two USB 3.0 ports, two SATA ports, and LPC. CPU boards and peripherals may be designed as Type 1, Type 2, or Universal (which only uses the common subset of signals between the two types, PCIe x1 and/or USB 2.0). The Type 2 pinout was not introduced until Version 2.0 of the specification (released in 2011). PCI/104-Express products introduced prior to 2011 will be either Type 1 or Universal, but may not be explicitly labeled as such. A Type 1 bus is incompatible with Type 2 peripherals, or vice versa. The specification requires the system to remain in reset and not boot in the case of a Type mismatch (no physical damage will occur). Universal peripheral boards may be used with either Type 1 or Type 2 pinouts. Because the PCIe bus connector is surface-mount, not through-hole, it is also possible for a board to use different bus pinouts on the top side of the board vs the bottom side. For example, a CPU board may have a Type 1 bottom PCIe connector and a Type 2 top PCIe connector. Such a CPU board would be compatible with Type 1 and/or Universal peripherals on the bottom, and compatible with Type 2 and/or Universal peripherals on the top. Similar to PC/104-Plus, a PCI/104-Express CPU boards will provide active communication on both PCI and PCIe buses. A PC/104-Express CPU board may be used with PCI-104 and PC/104-Plus peripheral modules. However, a PCI/104-Express peripheral module will communicate on the PCIe bus only; the PCI connector is simply a pass-through connector for stackability. A PC/104-Express peripheral module may not be used with a PCI-104 or PC/104-Plus CPU board (unless an ISA bridge device is used). PCI/104-Express incorporates link shifting, which eliminates the need for the PCI slot selection switches/jumpers found on PCI-104 and PC/104-Plus peripherals. Some peripheral boards re-populate the PCIe links, which allows the stack to have additional peripheral boards beyond the initial set