Are expansion cards an input or output device?

Answer 1

Input I would have thought.

If you are refering to the big readers of the 80-column punched card then they are Input devices. But many of these devices were made so that they could also be used for output - ie for punching cards - these are both Input and Output devices.
A card reader is an INPUT (not imput) device.

Whenever you are trying to categorize a device as Input or Output, think of how it looks from the computer.

If the computer is transmitting data to it, it is an Output device.

If the computer is receiving data from it, it is an Input device.

Answer 2

It depends on the type of expansion slotslike PCI ports can be used to connect devices that accept Input (Serial Cards)or Output(PCI Parallel Cards) and AGP Expansion slotused for connecting Graphics Display (only Output)

Answer 3

They can be both, as with soundcards, you can input a microphone to them to input sound, but can also connect speakers, to output sound.

Answer 4

A video card is an output device it is used to drive the computer's display.

Answer 5

It's both... A network card is intended to allow a remote computer to 'talk' to a file-server. The data is both sent, and received by both computers.