PCLATH stands for Program Counter LATch High (byte). In this case latch refers to the digital design technique where you have a register that holds bit(s) unti

PCLATH stands for Program Counter LATch High (byte). In this case latch refers to the digital design technique where you have a register that holds bit(s) until some other event happens. The event in this case is a write to PCL. Once the event occurs, PCLATH is transferred to PCH synchronously/atomically with the write to PCL.