Register type represents a hardware register present on a microcontroller at a specific address location. Typically ARM based microcontrollers have memory mapped 32 bit registers. Registers can be used in the same way as variables of the type Integer. However the key difference is that the compiler will always generate code to access the Register either to read or store the value. If needed current value of the Register can be assigned to the Integer variable for later use. All of the registers are declared in the runtime module specific to the microcontroller.

Example:

'Timer 0IR Interrupt Register

Declare Register T0IR As Integer @ &hE0004000

' Assign HEX value

T0IR = &h0

'Assign binary value

T0IR = &b00000000000000000000000000000000

Wikipedia: Hardware register