Artesyn MITX-CORE-820 Installation and Use (July 2014) - Manual (Page 104)

Firmware
MITX-CORE-820 Installation and Use (6806800M10H) 104
registers which selects the register within the bank. Accessing the data register while the index
register holds a value of 30h or higher actually accesses the logical device configuration
registers. These are currently pointed to by the index register within the logical device
currently selected by the LDN register
Figure 6-2 Structure of Standard Configuration Register