Intel 386 User Manual

Intel386™ EX EMBEDDED MICROPROCESSOR USER’S MANUAL
E-30
E.2.2.5 Encoding of Operation Direction (d) Field
In many two-operand instructions the d field is present to indicate which operand is considered
the source and which is the destination.
E.2.2.6 Encoding of Sign-Extend (s) Field
The s field occurs primarily to instructions with immediate data fields. The s field has an effect
only if the size of the immediate data is 8 bits and is being placed in a 16-bit or 32-bit destination.
E.2.2.7 Encoding of Conditional Test (tttn) Field
For the conditional instructions (conditional jumps and set on condition), tttn is encoded with n
indicating to use the condition (n=0) or its negation (n=1), and ttt giving the condition to test.
Table E-10. Encoding of Operation Direction (d) Field
d Direction of Operation
0 Register/Memory<--Register
“reg” field indicates source operand;
“mod r/m” or “mod ss index base” indicates destination operand.
1 Register<--Register/Memory
“reg” field indicates destination operand;
“mod r/m” or “mod ss index base” indicates source operand.
Table E-11. Encoding of Sign-Extend (s) Field
s Effect on Immediate Data8 Effect on Immediate Data 16|32
0 None None
1 Sign-Extend Data8 to fill
16-bit or 32-bit destination
None
Table E-12. Encoding of Conditional Test (tttn) Field
Mnemonic Condition tttn
O
NO
B/NAE
NB/AE
E/Z
NE/NZ
BE/NA
NBE/A
S
NS
P/PE
NP/PO
L/NGE
NL/GE
LE/NG
NLE/G
Overflow
No Overflow
Below/Not Above or Equal
Not Below/Above or Equal
Equal/Zero
Not Equal/Not Zero
Below or Equal/Not Above
Not Below or Equal/Above
Sign
Not Sign
Parity/Parity Even
Not Parity/Parity Odd
Less Than/Not Greater or Equal
Not Less Than/Greater or Equal
Less Than or Equal/Greater Than
Not Less or Equal/Greater Than
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111

Intel 386 Specifications

General

Brand	Intel
Model	386
Category	Computer Hardware
Language	English