However, might represent a location that can be changed by other elements of the computer system at any time, such as a hardware register of a device connected to the CPU.

SystemVerilog names this type "logic" to remind users that it has this extra capability and is not a hardware register.

Exhaustive - 1:1 mapping of unique addresses to one hardware register (physical memory location)

Partial - n:1 mapping of n unique addresses to one hardware register.

It uses a hardware register renaming mechanism rather than simple register windowing for parameter passing.

The keyword "'reg"' does not necessarily imply a hardware register.

Programs should avoid reading the hardware register directly unless the program is certain the register is read at a time insuring the value is valid.

The status register is a hardware register which contains information about the state of the processor.

TIA's fifth object called the "ball" was removed, but CTIA can combine the four missiles to form a fifth Player of a different color by setting a hardware register.

But both systems used "graphics indirection" where each playfield color is represented by a hardware register allowing those playfield colors to be selected from a palette of 256.