Double Byte Data

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The Double Data Flag (D) is set when the SDBD instruction is executed. This flag causes the next instruction, if it is an Indirect mode instruction, to load the 16-bit operand from the lowest 8 bits of two consecutive memory locations, rather than all 16-bits of a single memory location. Note that the D flag only remains set for the next executed opcode, regardless of whether of not the next opcode is actually affected by the status of the Double Data Flag. After execution of the next opcode, the Double Data Flag is automatically cleared.

The behavior of the following opcodes is affected by the status of the Double Data Flag.

MVI@
ADD@
SUB@
CMP@
AND@
XOR@