MC68306 Motorola, MC68306 Datasheet - Page 93

• Manufacturer Part Number: MC68306
• Description: Integrated EC000 Processor
• Manufacturer: Motorola

5.2 REGISTER DESCRIPTION
The following paragraphs describe the registers in the MC68306. The address of the
register is listed above the register. The numbers in the first row are the bit positions of
each bit in the register. The second row is the bit mnemonic. The reset value for each bit
is listed beneath the bit mnemonic. Where the reset value is U, the value is indeterminate
after power-up, and not affected by reset.
5.2.1 System Register
The system register controls system functions. The value of the AMODE bit after reset is
the value of the AMODE pin latched at reset.
BTERR—Bus Timeout Error
BTEN—Bus Timeout Enable
AMODE—Address Mode
MOTOROLA
This bit is read-only, and is cleared when read. Writes to this bit are ignored.
This bit is used to enable the bus timeout timer.
This bit selects the function of the multiplexed address and chip select pins. The
address mode pin is latched at the end of reset, so the value must be valid and stable at
this time. Writes to this bit are ignored.
0 = No bus timeout bus error.
1 = Bus timeout bus error occurred.
0 = Bus timeout timer is disabled.
1 = Bus timeout timer is enabled.
0 = Address lines selected.
1 = Chip select lines selected.
FFFFFFFE
BTERR
RESET
15
0
:
BTEN
14
0
MC68306 USER'S MANUAL
13
0
0
AMOD
AMOD
12
E
E
11
0
0
DUIPL
10
2
1
SUPERVISOR ONLY
DUIPL
9
1
0
DUIPL
8
0
0
5- 3