This DEP interface card for the Basic Controller buffers the data being sent from the data entry panel and the controller.

An LED is provided on the front of the card, when it blinks it's being updated with data. The CPU can parallel-lead data into a small RAM on the card, which is ready to send to the DEP by serial port. The serial data read is then loaded into the RAM, ready for the CPU to read it.

The newer version of the DEP interface card, prior to the introduction of the Universal Controller, is the 30750318-003, and is also available from WPC.