# PT2 IRIS/M.BLACK LINK ROM Trace

This note records the ROM evidence for the bench-visible
`IRIS/M.BLACK LINK` lamp.

## Confirmed Host Trigger

The isolated bench trigger is:

```text
00 00 13 40 00 09  ; command 0, selector 0x0013, value 0x4000
```

Command 0 mirrors nonzero selector writes into both `E000[selector]` and
`E800[selector]`, then queues the selector for internal processing. For this
frame that means:

```text
E000[0x0013] = 0x4000
E800[0x0013] = 0x4000
```

The current-table word is `E800 + 2 * 0x0013 = H'E826`.

## Selector Handler

The selector dispatch table maps selector `0x0013` to `H'2E06`.

Focused linear decode:

```text
H'2E06  BTST.W #15, @H'E826
        set/clear F791.6 and F713.4

H'2E1E  BTST.W #14, @H'E826
        set/clear F791.5 and F716.7
```

Bench labels:

| Selector value | ROM latch bits | Visible result |
| --- | --- | --- |
| `0x8000` | `F791.6`, `F713.4` | far-right `SLAVE` lamp |
| `0x4000` | `F791.5`, `F716.7` | `IRIS/M.BLACK LINK` lamp |
| `0x0000` | clears both bit groups through `H'2E06` | both latch groups clear |

## Other Trigger Path

There is also a local panel-input path:

```text
F006.7 / F6DB.7 -> H'200E -> H'E826 bit14 -> loc_3E54 queues selector 0x0013
```

At `H'200E`, the ROM checks `F6DB.7` and requires `F731 <= 3`. It then uses
`F791.5` as a current-state toggle:

- if `F791.5` is clear, it sets `H'E826.14`,
- if `F791.5` is set, it clears `H'E826.14`,
- in both cases it calls `loc_3E54` with selector `0x0013`.

This is not a separate lamp driver. It feeds the same `E800[0x0013].14`
state consumed by the selector handler.

## Practical Meaning

The strongest current model is:

- CCU/host can drive the lamp directly by sending selector `0x0013` value
  `0x4000` through command 0.
- The panel can also toggle/report the same state through a local input lane,
  but only when the relevant session/page gate is open.
- No other decoded selector currently appears to directly set the same
  `F791.5` plus `F716.7` latch pair.

Generated semantics now label selector `0x0013`, `E800[0x0013]`, and the
`IRIS/M.BLACK LINK` / `SLAVE` bit meanings so pseudo-code output does not leave
this as a generic table write.