11-13
MATH COPROCESSING
11.4.4 Exception Trapping
The 80C187 detects six error conditions that can occur during instruction execution. The 80C187
can apply default fix-ups or signal exceptions to the microprocessor’s ERROR pin. The processor
tests ERROR at the beginning of numerics instructions, so it traps an exception on the next at-
tempted numerics instruction after it occurs. When ERROR tests active, the processor executes a
Type 16 interrupt.
There is no automatic exception-trapping on the last numerics instruction of a series. If the last
numerics instruction writes an invalid result to memory, subsequent non-numerics instructions
can use that result as if it is valid, further compounding the original error. Insert the FNOP in-
struction at the end of the 80C187 routine to force an ERROR check. If the program is written in
a high-level language, it is impossible to insert FNOP. In this case, route the error signal through
an inverter to an interrupt pin on the microprocessor (see Figure 11-4). With this arrangement,
use a flip-flop to latch BUSY upon assertion of ERROR. The latch gets cleared during the excep-
tion-handler routine. Use an additional flip-flop to latch PEREQ to maintain the correct hand-
shaking sequence with the microprocessor.
11.5 EXAMPLE MATH COPROCESSOR ROUTINES
Example 11-1 shows the initialization sequence for the 80C187. Example 11-2 is an example of
a floating point routine using the 80C187. The FSINCOS instruction yields both sine and cosine
in one operation.
Содержание 80C186EA
Страница 1: ...80C186EA 80C188EA Microprocessor User s Manual...
Страница 2: ...80C186EA 80C188EA Microprocessor User s Manual 1995...
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Страница 20: ...1 Introduction...
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Страница 28: ...2 Overview of the 80C186 Family Architecture...
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Страница 80: ...3 Bus Interface Unit...
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Страница 130: ...4 Peripheral Control Block...
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Страница 140: ...5 ClockGenerationand Power Management...
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Страница 166: ...6 Chip Select Unit...
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Страница 190: ...7 Refresh Control Unit...
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Страница 206: ...8 Interrupt Control Unit...
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Страница 239: ...INTERRUPT CONTROL UNIT 8 32...
Страница 240: ...9 Timer Counter Unit...
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Страница 266: ...10 Direct Memory Access Unit...
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Страница 295: ...DIRECT MEMORY ACCESS UNIT 10 28...
Страница 296: ...11 Math Coprocessing...
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Страница 314: ...12 ONCE Mode...
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Страница 318: ...A 80C186 Instruction Set Additions and Extensions...
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Страница 330: ...B Input Synchronization...
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Страница 334: ...C Instruction Set Descriptions...
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Страница 383: ...INSTRUCTION SET DESCRIPTIONS C 48...
Страница 384: ...D Instruction Set Opcodes and Clock Cycles...
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Страница 408: ...Index...
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