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 |
|---|---|---|---|
| SD | D register | 1 | 18 |
| SP | Program counter | 2 | 28 |
| SB | B register | 3 | 38 |
| SL | L register | 4 | 48 |
| SA | A register | 5 | 58 |
| ST | T register | 6 | 68 |
| SX | 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
- Norsk Data Document ND–06.014.02 ND-100 REFERENCE MANUAL Page 3-37
- Norsk Data Document ND–06.029.01 ND-110 Instruction Set Pages 39-40