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Syntax:
reg = DM ( <addr> ) ;
Permissible registers
AX0
MX0
SI
SB
CNTR
AX1
MX1
SE
PX
OWRCNTR (write only)
AY0
MY0
SR1
ASTAT
RX0
AY1
MY1
SR0
MSTAT
RX1
AR
MR2
I0-I7
TX0
MR1
M0-M7
IMASK
TX1
MR0
L0-L7
ICNTL
IFC(write only)
Example:
SI = DM( ad_port0 );
Description:
The Read instruction moves the contents of the data
memory location to the destination register. The addressing mode is direct
addressing (designated by an immediate address value or by a label). The
data memory address is stored directly in the instruction word as a full 14-
bit field. The contents of the source are always right-justified in the
destination register after the read (bit 0 maps to bit 0).
Note that whenever MR1 is loaded with data, it is sign-extended into
MR2.
Status Generated:
None affected.
Instruction Format:
Data Memory Read (Direct Address), Instruction Type 3:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
1 0 0 0 RGP ADDR REG
ADDR contains the direct address to the source location in Data Memory.
RGP (Register Group) and REG (Register) select the destination register
according to the Register Selection Table (see Appendix A).
MOVE
DATA MEMORY READ (Direct Address)