Intel 80286 User Manual

TABLE OF CONTENTS
CHAPTER 1 Page
OVERVIEW OF NUMERIC PROCESSING
Introduction to the 80287 Numeric Processor Extension ............................................. 1-1
Performance ...................... ........... ....... ................................................ ............ ........... 1-1
Ease of Use ................................................................................................................. 1-2
Applications . ................................................................................................................ 1-3
Upgradability ............................................................................................................... 1-4
Programming Interface ................................................. ..... ......................................... 1-5
Hardware Interface .....................................................................................................
1-6
80287 Numeric Processor Architecture ........................................................................ 1-8
The
NPX Register Stack ......................... '.................................................................... 1-8
The
NPX Status Word ................................................................................................ 1-9
Control Word . .............................................................................................................. 1-10
The
NPXTag Word ..................................................................................................... 1-12
The
NPX Instruction and Data Pointers ..................................................................... 1-12
Computation Fundamentals ........................................................................................... 1-14
Number System .......................................................................................................... 1-14
Data Types and Formats ............................................................................................ 1-15
Binary Integers ........................................................................................................ 1-17
Decimal Integers ..................................................... ..... ........................................... 1-17
Real Numbers .......................................................................................................... 1-17
Rounding Control ........................................................................................................ 1-18
Precision Control ........................................................................................................ 1-19
Infinity Control ............................................................................................................. 1-19
Special Computational Situations .................................................................................. 1-20
Special Numeric Values ............................................................................... ...............
1-21
Nonnormal Real Numbers ...................................................................................... 1-21
Denormals and Gradual Underflow.................................................................... 1-21
Un normals-Descendents of Denormal Operands ........................................... 1-23
Zeros and Pseudo Zeros ....... ....................................................... ............... ........... 1-24
Infinity ...................................................................................................................... 1-25
NaN (Not a Number) ................................................................................................ 1-25
Indefinite .................................................................................................................. 1-29
Encoding of Data Types .......... ....... ................................................ ........................
1-29
Numeric Exceptions .................................................................................................... 1-33
Invalid Operation ..................................................................................................... 1-33
Zero Divisor ............................................................................................................. 1-33
Denormalized Operand ........................................................................................... 1-34
Numeric Overflow and Underflow.......................................................................... 1-34
Inexact Result .......................................................................................................... 1-34
Handling Numeric Errors ........................................... ............................................. 1-34
Automatic Exception Handling .............................................. .............................. 1-37
Software Exception Handling .............................................................................. 1-38
CHAPTER 2
PROGRAMMING NUMERIC APPLICATIONS
The 80287 NPX Instruction Set ..................................................................... ;............... 2-1
Compatibility with the 8087 NPX ................................................................................ 2-1
Numeric Operands ...................................................................................................... 2-1
Data Transfer Instructions ......................................................................... ................. 2-2
Arithmetic Instructions ................................................................................................ 2-4
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Intel 80286 Specifications

General

Processor Type	Microprocessor
Clock Speed	6 MHz to 25 MHz
Transistor Count	134, 000
Addressable Memory	16 MB
Instruction Set	x86
Architecture	x86
Data Bus Width	16-bit
Address Bus Width	24-bit
Operating Modes	Real mode, Protected mode
Process Technology	1.5 µm
Voltage	5V
Introduced	1982
Package	68-pin PGA