Table 2-2.
Local Bus Interface Signals
Pin
Type
Name
Description
5-18
Bidirectional
A<0:13>
----
20-21
Bidirectional
A<14:15>
----
23-30
Bidirectional
A<16:23>
CPU address, bits 0-23. A0 is also known as -BLE.
These signals are driven by the CPU during CPU
generated bus cycles, by the 82C836 during Refresh
and DMA cycles, and by the add-in card Bus Master
(via address buffers) during Master cycles.
58
Bidirectional
MODA0
Modified A0 is the internally latched state of CPU
address bit A0 during CPU generated bus cycles. The
82C836 toggles this bit during conversion cycles. The
82C836 also controls MODA0 during Refresh and
DMA cycles, and the add-in card Bus Master controls
it (via address buffers) during Master cycles.
98
Bidirectional
MODA20
Modified A20 is gated A20 from the 82C836’s gate
A20 logic and should be used instead of CPU A20.
MODA20 is an input during Master cycles.
33
Bidirectional
-BHE
Byte High Enable is an input from the 80386sx during
CPU and Master cycles, and an output during DMA
cycles. -BHE and A0 indicate the type of bus transfer.
-BHE is pulled high internally.
BHE
A0
Function
0
0
Word transfer
0
1
Odd byte transfer
1
0
Even byte transfer
1
1
Reserved
160
Bidirectional
D00
----
158
Bidirectional
D01
----
156
Bidirectional
D02
----
154
Bidirectional
D03
----
152
Bidirectional
D04
----
150
Bidirectional
D05
----
148
Bidirectional
D06
----
146
Bidirectional
D07
----
159
Bidirectional
D08
----
157
Bidirectional
D09
----
155
Bidirectional
D10
----
153
Bidirectional
D11
----
151
Bidirectional
D12
----
149
Bidirectional
D13
----
147
Bidirectional
D14
----
145
Bidirectional
D15
CPU data bus, bits 0 to 15.
Pin Assignments
Signal Descriptions
I
Chips and Technologies, Inc.
P R E L I M I N A R Y
Revision 3.0
2-3