Freescale Semiconductor, Inc.
Operating Modes
Internal Resource Mapping
PPAGE — (Program) Page Index Register
$00FF
Bit 7
6
0
0
5
0
0
4
0
0
3
0
0
2
PIX2
0
1
Bit 0
0
0
PIX1
0
PIX0
0
RESET:
Read and write: anytime.
This register determines the active page viewed through
MC68HC912DG128 windows.
CALL and RTC instructions have a special single wire mechanism to
read and write this register without using an address bus.
5.5.9 Miscellaneous System Control Register
Additional mapping and external resource controls are available. To use
external resources the part must be operated in one of the expanded
modes.
MISC — Miscellaneous Mapping Control Register
$0013
Mode
Bit 7
ROMTST
0
6
NDRF
0
5
RFSTR1
0
4
RFSTR0
0
3
EXSTR1
1
2
EXSTR0
1
1
ROMHM
0
Bit 0
ROMON
0
RESET:
RESET:
Exp mode
peripheral or
SC mode
0
0
0
0
1
1
0
1
Normal modes: write once; Special modes: write anytime. Read
anytime.
ROMTST — FLASH EEPROM Test mode
In normal modes, this bit is forced to zero.
0 = 16K window for Flash memory is located from $8000–$BFFF
1 = 32K window for Flash memory is located from $8000–$FFFF
MC68HC912DG128 — Rev 3.0
Technical Data
Operating Modes
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