AT&T 3B2/300 Technical Reference Manual page 314

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OPl
OP2
OP3
Bits 09-07 is the Operand Specifier 1 (OPl) field. OPl specifies whether the first
source operand is a MAU register, a memory-based operand of a given size, or
nonexistent (no operand). The value of this field is as follows.
BITS 09 - 07 OPERAND LOCATION
000 REGISTER FD
001 REGISTER Fl
010 REGISTER F2
011
REGISTER F3
100
MEMORY-BASED SINGLE WORD
101 MEMORY-BASED DOUBLE WORD
110
MEMORY-BASED TRIPLE WORD
111 NO OPERAND
Bits 06-04 is the Operand Specifier 2 (OP2) field. OP2 specifies whether the
second source operand is a MAU register, a memory-based operand of a given size,
or nonexistent (no operand). The value of this field is as follows.
BITS 06 - 04 OPERAND LOCATION
000
REGISTER FO
001 REGISTER Fl
010 REGISTER F2
011
REGISTER F3
100 MEMORY-BASED SINGLE WORD
101
MEMORY-BASED DOUBLE WORD
110 MEMORY-BASED TRIPLE WORD
111 NO OPERAND
Bits 03-00 are the Operand Specifier 3 (OP3) field. OP3 specifies whether the
destination operand is a MAU register, a memory-based operand of a given size, or
nonexistent (no operand). Even though the register destinations are specified as
single, double, or double-extended, the result is stored in the registers in
double-extended precision. The precision designations are used for rounding and
checking for underflow and overflow. The value of this field is as follows.
OPERAND DESTINATION
BITS 03 - 00
REGISTER PRECISION
0000 FD SINGLE
0001
Fl SINGLE
0010 F2 SINGLE
0011 F3 SINGLE
0100 FO DOUBLE
0101 Fl DOUBLE
0110 F2
DOUBLE
0111 F3 DOUBLE
1000
FO
DOUBLE-EXTENDED
1001 Fl DOUBLE-EXTENDED
1010 F2 DOUBLE-EXTENDED
1011 F3
DOUBLE-EXTENDED
1100 DR MEMORY-BASED SINGLE WORD
1101 DR MEMORY-BASED DOUBLE WORD
1110 DR MEMORY-BASED TRIPLE WORD
1111 NONE NO OPERAND
FUNCTIONAL DESCRIPTION 3-61