42
Pin Name
Pin #
Type
Description
UA15
UA14
UA13
UA12
UA11
UA10
UA9
UA8
116
117
118
119
120
121
122
123
I
System Controller Address 15 8 Bus:
This bus is the upper 8-bits of the 16-
bit system controller address. In register access mode (UCS0# asserted),
UA15
are not decoded.
UA7
UA6
UA5
UA4
UA3
UA2
UA1
UA0
124
125
126
127
128
129
130
131
I
System Controller Address 7 0 Bus:
This bus is the lower 8-bits of the 16-
bit system controller address when non-multiplexed mode is enabled (see
UALE description). In Non-Multiplexed Mode, U
ust be grounded.
UAD7
UAD6
UAD5
UAD4
UAD3
UAD2
UAD1
UAD0
104
103
102
101
100
99
98
97
I/O
System Controller Address 7 0/Data Bus:
This bi-directional bus transfers
8-bit data. When multiplexed mode is enabled (see UALE description),
UAD7 0 also functions as the lower 8-bits of the system controller address
bus. UAD7 0 is high-impedance when not used to transfer data or
addresses.
URD# /
UR/W#
105
I
S
Microcontroller Read Strobe:
In X86 Mode, URD# is the read data strobe.
Read or Write Status:
In Motorola Mode, UR/W# high indicates that a read
is occurring when UDS# is asserted. UR/W# low indicates that a write is
occurring when UDS# is asserted.
UWR# /
UDS#
106
I
S
Microcontroller Write Strobe:
In X86 Mode, UWR# is the write data
strobe.
Data Strobe:
In Motorola Mode, UDS# is the data strobe. Signal UR/W#
determines whether a read or write is occurring when UDS# is asserted.
SYSTEM CONTROLLER INTERFACE