Input-Output Instructions (Microcontrollers)

2.6
The last class of instructions for the 6812, the input-output or I/O class, is easy to describe because there aren’t any! With the 6812 a byte is transferred between an accumulator and a register in an I/O device through a memory location chosen by hardware. The ldaa instruction with that location then inputs a byte from the register of the I/O device to accumulator A, while the staa instruction with that location does the corresponding output of a byte. Other instructions, such as movb, movm, rol, ror, dec, inc, and clr, may be used as I/O instructions, depending on the particular device. We look more closely at all of these issues in topic 11.