4a
- When hooking up a device, we have three registers
- Just like memory
- Data Register
- Control Register
- Status Register
- This collection of registers is called in I/O Port
- If we map the I/O Port to a memory address, this is called
memory mapped I/O
- Other architectures include special I/O instructions for accessing
the I/O ports
- This is called isolated I/O
- In general
- Wait for the controller to finish the last command
- Place values in the data register
- Set the control register