80C286_08 Datasheet, PDF (12/60 Pages) Intersil Corporation – High Performance Microprocessor with Memory Management and Protection

80C286
Combinations of these three address elements define the six
memory addressing modes, described below.
DIRECT MODE: The operand's offset is contained in the
instruction as an 8 or 16-bit displacement element.
REGISTER INDIRECT MODE: The operand's offset is in
one of the registers SI, Dl, BX or BP.
BASED MODE: The operand's offset is the sum of an 8 or
16-bit displacement and the contents of a base register (BX
or BP).
INDEXED MODE: The operand's offset is the sum of an 8 or 16-
bit displacement and the contents of an index register (SI or Dl).
BASED INDEXED MODE: The operand's offset is the sum
of the contents of a base register and an index register.
BASED INDEXED MODE WITH DISPLACEMENT: The
operand's offset is the sum of a base register's contents, an
index register's contents, and an 8 or 16-bit displacement.
Data Types
The 80C286 directly supports the following data types:
Integer:
A signed binary numeric value contained in an 8-
bit byte or a 16-bit word. All operations assume a
2's complement representation. Signed 32 and
64-bit integers are supported using the 80287
Numeric Data Processor.
Ordinal: An unsigned binary numeric value contained in an
8-bit byte or 16-bit word.
Pointer: A 32-bit quantity, composed of a segment selec-
tor component and an offset component. Each
component is a 16-bit word.
String: A contiguous sequence of bytes or words. A string
may contain from 1 byte to 64K bytes.
ASClI:
A byte representation of alphanumeric and control
characters using the ASClI standard of character
representation.
BCD:
A byte (unpacked) representation of the decimal
digits 0-9.
Packed A byte (packed) representation of two decimal
BCD: digits 0-9 storing one digit in each nibble of the
byte.
Floating A signed 32, 64 or 80-bit real number representa-
Point: tion. (Floating point operands are supported using
the 80287 Numeric Processor extension).
Figure 5 graphically represents the data types supported by
the 80C286.
7
0
SIGNED
BYTE
SIGN BIT
MAGNITUDE
7
0
UNSIGNED
BYTE
MSB
MAGNITUDE
15 14 ⁺¹ 8 7 ⁰ 0
SIGNED
WORD
SIGN BIT
MSB
MAGNITUDE
SIGNED ₃₁
DOUBLE
WORD
(NOTE)
SIGN BIT
+3
MSB
+2 _{16 15} +1
00
MAGNITUDE
SIGNED
+7
63
+6 +5
48 47
+4 +3
32 31
+2 +1
16 15
QUAD
0
0
WORD
(NOTE)
SIGN BIT
MSB
+1
15
UNSIGNED
WORD
MSB
MAGNITUDE
0
0
MAGNITUDE
BINARY ^{7 +N 0}
CODED
DECIMAL
•••
(BCD)
BCD
DIGIT N
7 ⁺¹ 0 7 ⁰ 0
BCD
BCD
DIGIT 1 DIGIT 0
7 ^+N 0
7 ⁺¹ 0 7 ⁰ 0
ASCII
•••
ASCII
ASCII ASCII
CHARACTER_N CHARACTER₁ CHARACTER₀
7 ^+N 0
7 ⁺¹ 0 7 ⁰ 0
PACKED
BCD
•••
MOST
SIGNIFICANT DIGIT
LEAST
SIGNIFICANT DIGIT
7/15 ^+N 0
7/15 ⁺¹ 0 7/15 ⁰ 0
STRING
•••
BYTE/WORD N BYTE/WORD 1 BYTE/WORD 0
31 ⁺³
+1 _{16 15} +1
00
POINTER
SELECTOR
OFFSET
79 ^{+9 +8 +7 +6 +5 +4 +3 +2 +1 0} 0
FLOATING
POINT (NOTE)
SIGN BIT
EXPONENT
MAGNITUDE
FIGURE 5. 80C286 SUPPORTED DATA TYPES
NOTE: Supported by 80C286/80C287 Numeric Data Processor
Configuration
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