Intel 80286 User Manual

OVERVIEW OF NUMERIC PROCESSING
Table 1-17. Exception Conditions and Masked Responses
Condition
Masked Response
Invalid Operation
Source register is tagged empty (usually due
to stack underflow).
Destination
register is not tagged empty
(usually due to stack overflow).
One or both operands is a
NaN.
(Compare and test operations only): one or
both operands is a NaN.
(Addition operations only): closure
is affine and
operands are opposite-signed infinities;
or
closure is projective and both operands are 00
(signs immaterial).
(Subtraction operations only): closure
is affine
and operands are like-signed infinities;
or
closure is projective and both operands are 00
(signs immaterial).
(Multiplication operations only):
00 • 0; or 0 •
00.
(Division operations only): 00 -;- 00; or 0 -;- 0;
or 0 -;- pseudo zero; or divisor is denormal or
unnormal.
(FPREM instruction only): modulus (divisor)
is
unnormal or denormal; or dividend is 00.
(FSQRT instruction only): operand is nonzero
and negative;
or operand is denormal or
unnormal; or closure is affine and operand is
-00; or closure is projective and operand is
00.
(Compare operations only): closure is projec-
tive and
00 is being compared with 0, a normal,
or
00.
(FTST instruction only): closure is projective
and operand is
00.
(FIST, FISTP instructions only): source regis-
ter
is empty, a NaN, denormal, unnormal, 00,
or exceeds representable range of destina-
tion.
(FBSTP instruction only): source register
is
empty, a NaN, denormal, unnormal, 00, or
exceeds 18 decimal digits.
(FST, FSTP instructions only): destination is
short
or long. real and source register is an
unnormal with exponent in range.
(FXCH Instruction only): one or both registers
is tagged empty.
1-35
Return real indefinite.
Return real indefinite (overwrite destination
value).
Return
NaN with larger absolute value (ignore
signs).
Set condition codes
"not comparable."
Return real
indefinite.
Return real indefinite.
Return real indefinite.
Return real indefinite.
Return real indefinite, set condition code =
"complete remainder."
Return real
indefinite.
Set condition code = "not comparable."
Set condition code
= "not comparable."
Store integer
indefinite.
Stored packed decimal indefinite.
Store real indefinite.
Change empty register(s) to real indefinite and
then'perform exchange.
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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