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11-7
MATH COPROCESSING
11.3.2 80C187 Data Types
The microprocessor/math coprocessor combination supports seven data types:
• Word Integer — A signed 16-bit numeric value. All operations assume a 2’s complement
representation.
• Short Integer — A signed 32-bit numeric value (double word). All operations assume a 2’s
complement representation.
• Long Integer — A signed 64-bit numeric value (quad word). All operations assume a 2’s
complement representation.
• Packed Decimal — A signed numeric value contained in an 80-bit BCD format.
• Short Real — A signed 32-bit floating point numeric value.
• Long Real — A signed 64-bit floating point numeric value.
• Temporary Real — A signed 80-bit floating point numeric value. Temporary real is the
native 80C187 format.
Figure 11-1 graphically represents these data types.
11.4 MICROPROCESSOR AND COPROCESSOR OPERATION
The 80C187 interfaces directly to the microprocessor (as shown in Figure 11-2) and operates as
an I/O-mapped slave peripheral device. Hardware handshaking requires connections between the
80C187 and four special pins on the processor: N
CS, BUSY, PEREQ and ERROR. These pins
are multiplexed with MCS3
, TEST, MCS0, and MCS1, respectively. When the processor leaves
reset, the presence of the 80C187 automatically places the processor in Enhanced Mode and con-
figures the pins correctly. MCS2
retains its function as a chip-select and the processor retains the
wait state and ready programming for the entire mid-range memory block, even though MCS0
,
MCS1
and MCS3 are no longer available.