Destination register

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Destination register (abbr. <dr>) is encoded in bits 2..0 of Register Operation (ROP) instructions.

The destination registers are specified as follows:

MAC mnemonic Register name Value Octal value to add to ROP instruction
DD D register 1 18
DP Program counter 2 28
DB B register 3 38
DL L register 4 48
DA A register 5 58
DT T register 6 68
DX X register 7 78

If no destination register is specified (value: 0) the instruction is normally transformed to a NOP (no-operation). EXIT, EXR, RDIV, MIX3 are exceptions to this and RADD clears the carry indicator (C) only.

References