Mode and Resource Mapping Registers
MC68HC812A4 Data Sheet, Rev. 7
Freescale Semiconductor
59
Normal modes: Write once
Special modes: Write anytime except the first time
EMD — Emulate Port D Bit
This bit only has meaning in special expanded narrow mode.
In expanded wide modes and special peripheral mode, PORTD, DDRD, KWIED, and KWIFD are
removed from the memory map regardless of the state of this bit.
In single-chip modes and normal expanded narrow mode, PORTD, DDRD, KWIED, and KWIFD are in
the memory map regardless of the state of this bit.
1 = If in special expanded narrow mode, PORTD, DDRD, KWIED, and KWIFD are removed from
the memory map. Removing the registers from the map allows the user to emulate the function
of these registers externally.
0 = PORTD, DDRD, KWIED, and KWIFD are in the memory map.
Normal modes: Write once
Special modes: Write anytime except the first time
EME — Emulate Port E Bit
In single-chip mode, PORTE and DDRE are always in the map regardless of the state of this bit.
1 = If in an expanded mode, PORTE and DDRE are removed from the internal memory map.
Removing the registers from the map allows the user to emulate the function of these registers
externally.
0 = PORTE and DDRE in the memory map
Normal modes: Write once
Special modes: Write anytime except the first time
5.4.2 Register Initialization Register
After reset, the 512-byte register block resides at location $0000 but can be reassigned to any 2-Kbyte
boundary within the standard 64-Kbyte address space. Mapping of internal registers is controlled by five
bits in the INITRG register. The register block occupies the first 512 bytes of the 2-Kbyte block.
Read: Anytime
Write: Once in normal modes; anytime in special modes
REG15–REG11 — Register Position Bits
These bits specify the upper five bits of the 16-bit register address.
Address: $0011
Bit 7
654321
Bit 0
Read:
REG15
REG14
REG13
REG12
REG11
0
Write:
Reset:
00000000
Figure 5-2. Register Initialization Register (INITRG)