Intel 386 - Manual (Page 49)

Intel386™ EX EMBEDDED MICROPROCESSOR USER’S MANUAL
3-6
3.3 CORE Intel386 EX PROCESSOR INTERFACE
The Intel386 EX processor peripherals are connected to the Intel386 CX processor core through
an internal Bus Interface Unit (BIU). The BIU controls internal peripheral accesses and external
memory and I/O accesses. Because it has the BIU between the Intel386 CX processor core and
the external bus, the Intel386 EX processor bus timings are not identical to those of the Intel386
CX processor or Intel386 SX processor.
The Intel386 CX processor numeric coprocessor interface is maintained and brought out to the
Intel386 EX processor pins. The same I/O addresses used on the Intel386 SX processor are used
on the Intel386 EX processor, even though there are more address lines. The A23 line is high for
coprocessor cycles. Refer to “Interface To Intel387™ SX Math Coprocessor” on page 6-38 for
more details.