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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: NCS, 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.
MATH COPROCESSING
11-7
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