MC68HC12 Datasheet, PDF (98/478 Pages) Motorola, Inc – The MC68HC912DT128A microcontroller unit (MCU) is a 16-bit device composed of standard on-chip peripherals including a 16-bit central processing unit

Resource Mapping
Table 6-6. EXSTR Stretch Bit Definition
EXSTR1
0
0
1
1
EXSTR0
0
1
0
1
Number of E Clocks
Stretched
0
1
2
3
ROMHM — Flash EEPROM only in second Half of Map
This bit has no meaning if ROMON bit is clear.
0 = The 16K byte of fixed Flash EEPROM in location $4000-$7FFF
can be accessed.
1 = Disables direct access to 16K byte Flash EEPROM from
$4000-$7FFF in the memory map. The physical location of
this16K byte Flash can still be accessed through the Program
Page window.
In special mode and with ROMTST bit set, this bit will allow overlap of
the four 32K Flash arrays and overlap the four 4-byte Flash register
space in the same map space to be able to program all arrays at the
same time.
0 = The four 32K Flash arrays are accessed with four pages for
each.
1 = The four 32K Flash arrays coincide in the same space and are
selected at the same time for programming.
CAUTION: Bit must be cleared before reading any of the arrays or registers.
ROMON — Enable Flash EEPROM
These bits are used to enable the Flash EEPROM arrays.
0 = Disables Flash EEPROM in the memory map.
1 = Enables Flash EEPROM in the memory map.
Technical Data
98
Resource Mapping
MC68HC912DT128A — Rev 4.0
MOTOROLA