MC68306FC16 Datasheet, PDF (93/191 Pages) Motorola, Inc – Integrated EC000 Processor

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.
FFFFFFFE
15
14
13
12
11
10
9
8
BTERR BTEN
0 AMOD 0 DUIPL DUIPL DUIPL
E
2
1
0
RESET
:
0
0 AMOD 0
1
0
0
0
E
SUPERVISOR ONLY
BTERR—Bus Timeout Error
This bit is read-only, and is cleared when read. Writes to this bit are ignored.
0 = No bus timeout bus error.
1 = Bus timeout bus error occurred.
BTEN—Bus Timeout Enable
This bit is used to enable the bus timeout timer.
0 = Bus timeout timer is disabled.
1 = Bus timeout timer is enabled.
AMODE—Address Mode
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 = Address lines selected.
1 = Chip select lines selected.
MOTOROLA
MC68306 USER'S MANUAL
5-3