Embedded Open Modular Architecture/EOMA68/Passthrough
These cards allow access to the features of Motherboard Chassis devices performing little or no conversion of signals and passing them through to the EOMA-PCMCIA connector. Examples include:
- A tablet with a passthrough card could be used as a portable LCD monitor, including its touchscreen converted for use as a USB device.
- A large LCD Screen with a passthrough card could be used as a LCD monitor, with the ability to upgrade it simply by swapping the passthrough card for a TV card or CPU card: the LCD Screen becomes a fully-functioning computer or a TV.
- A keyboard with a passthrough card is a plain keyboard, perhaps with extra USB ports. Removal of the passthrough card and insertion of a CPU card turns the keyboard into a fully-functioning computer.
- A laptop with a passthrough card is a strange concept! It offers the use of the keyboard and mouse as USB devices, allowing it to be plugged into a Desktop PC, and also allows the LCD screen to be used for display purposes - again on a Desktop PC or other suitable device.
These two examples are incredibly simple. Connectors for Ethernet, USB and eSATA are simply passed straight through - literally - to the PCMCIA connector. HDMI input is converted into 24-pin RGB/TTL: a suitable IC is the Texas Instruments TFP401a. More advanced versions would convert HDMI Audio into, for example, USB Audio.