Design Considerations; Interface To Intel387™ Sx Math Coprocessor - Intel 386 User Manual

Intel386™ EX EMBEDDED MICROPROCESSOR USER'S MANUAL
6.6

DESIGN CONSIDERATIONS

•
Upon reset, UCS# is configured as a 16-bit chip-select signal. If the Boot device is only an
8-bit device, then BS8# must be asserted whenever UCS# is active (until the UCS region
can be reprogrammed to reflect an 8-bit region). One way of doing this is by connecting the
UCS# pin directly to the BS8# pin, if there are no other devices that need to use the BS8#
pin. If UCS# is tied directly to BS8#, then the UCS region need not be programmed to
reflect an 8-bit region.
•
Since LBA# may be used as an output-enable by both the internal and external READY#
buffers, care must be taken in selecting the external READY# buffer to minimize
contention on the READY# signal caused by differences in buffer characteristics.
6.6.1 Interface To Intel387™ SX Math Coprocessor
The Intel387 SX Math Coprocessor is an extension to the Intel386 EX embedded processor ar-
chitecture. The combination of the Intel387 SX Math Coprocessor with the Intel386 EX embed-
ded processor dramatically increases the processing speed of computer application software that
uses high performance floating-point operations.
An internal Power Management Unit enables the Intel387 SX Math Coprocessor to perform float-
ing-point operations while maintaining very low power consumption. The internal Power Man-
agement Unit effectively reduces power consumption by 95% when the coprocessor is idle.
This section describes special considerations for interfacing the Intel387 SX Math Coprocessor
with the Intel386 EX embedded processor. For complete information, refer to the Intel387™ SX
Math Coprocessor datasheet (Order number 240225).
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