Plugging Chips into Sockets

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Plugging Chips into Sockets

On the page "Components and Port Maps", we looked at the VHDL used to describe the instantiation of components in an architecture. Instantiating components in VHDL enables us to create a design hierarchy, it's just like plugging chips into a PCB. In our case, the MUX2I is the PCB, the AOI gate and the inverter (INV) are two chips. But what about the sockets? Let's look into instantiating components in a little more detail.

Component Declarations

Remember that the two component declarations (for INV and AOI) must match the corresponding entity declarations exactly with respect to the names, order and types of the ports. This is important because, as a hardware analogy, the component declaration is essentially a chip socket for the chip represented by the design entity - the entity declaration defines the pins of the chip.

Component Instantiation

So, instantiation is essentially a VHDL term for soldering a chip socket into a PCB. Instantiation also assumes that the socket contains the chip referenced by the same name as it is plugged into the PCB. However, for our purposes, we can think of component instantiation as plugging a chip into a PCB, ignoring whether it's socketed or not.

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