# PT2 Shutter Display Trace

This note collects the current ROM evidence for the shutter seven-segment display and related selector traffic.

## Confirmed Bench Mapping

The real panel responds to primary selector `0x008F`:

| Command 0 write | Meaning candidate | Observed panel result |
| --- | --- | --- |
| `00 01 0F 08 00 5C` | `E000[0x008F].11` | SHUTTER shows observed `EUS`, likely manual `EVS`; iris AUTO lamp on |
| `00 01 0F 10 00 44` | `E000[0x008F].12` | SHUTTER shows literal `OFF`; iris AUTO lamp on |
| `00 01 0F 18 00 4C` | bits 11 and 12 | likely `EVS` wins over `OFF`; iris AUTO lamp on |
| `00 01 0F 00 00 54` | clear candidate | not yet bench-confirmed |

Manual correlation:

- The RCP-TX7 manual has `OTHERS (1/6: SHUTTER)` with an `EVS` button.
- The RCP-TX7 menu table lists `EVS/ECS` under OTHERS for DXC-D30/D30P.
- A later CCU/RCP manual says the shutter display shows `EVS` when EVS is on and `OFF` when the shutter switch is off.

So `0x008F.11` is currently best labeled `shutter_evs_display_or_mode`, and `0x008F.12` is best labeled `shutter_off_display_or_mode`.

## Selector 0x008F ROM Path

Primary table address:

```text
selector 0x008F -> E000 + 2 * 0x008F = H'E11E
```

The OTHERS/SHUTTER menu handler is `H'6EE4`.

Important instructions:

```text
6F6E: BTST.W #11, @H'E11E
6F74: BSET.B #6, R0
6F76: BTST.W #12, @H'E11E
6F7C: BSET.B #4, R0
6F7E: MOV:G.B R0, @H'F711
```

This is the direct consumer seen so far. The current decompile does not show another static read of `H'E11E` outside this handler.

`H'6EE4` also programs local descriptor RAM before this:

```text
6EFD: F73E = H'088F
6F09: F74E = H'0800
6F0F: F742 = H'088F
6F1B: F752 = H'1000
```

Those descriptors match selector `0x008F` plus the two observed masks `0x0800` and `0x1000`, so the generic panel-output updater also appears to know about the same selector.

## Local Panel Trigger Path

`H'6EE4` can also generate a selector `0x008F` report/update from local OTHERS/SHUTTER controls:

```text
6F26: read F770 local action byte
6F2E: keep low two action bits
6F37: if action bit path and E400[0x008F].11 is enabled, set E800[0x008F] = 0x0800
6F45: if alternate action path and E400[0x008F].12 is enabled, set E800[0x008F] = 0x1000
6F53: R3 = 0x008F
6F64: call 3E54 report/target-frame builder
```

Practical meaning:

- The CCU can force the display state by writing `E000[0x008F]`.
- The RCP can also try to report local EVS/OFF changes through selector `0x008F`, but only when the secondary-table feature bits `E400[0x008F].11/.12` allow it.

## Adjacent Shutter Value Family

The periodic/control-change scanner at `H'15E0` processes changed input words collected by IRQ3 from the external panel chips. Around the shutter path it calls `H'19A2`, which compares a local delta against the current primary table value and, if changed, writes the `E800` current table and calls `H'3E54`.

Candidate selectors:

| Handler | Source RAM | Gate | Selector sent | Meaning candidate |
| --- | --- | --- | --- | --- |
| `H'17C9` | `F6AE/F6CE` | `E000[0x0093].12` | `0x00A3` | clear-scan/shutter value lane |
| `H'17FB` | `F6AC/F6CC` | `E000[0x0093].12` | `0x00A4` | clear-scan/shutter value lane |
| `H'182D` | `F6AA/F6CA` | `E000[0x0093].5`, `F717.2` clear | `0x00A5` | shutter value lane |
| `H'182D` | `F6AA/F6CA` | `F717.2` set | `0x00D8` | alternate/DXC-637 shutter lane |
| `H'1891` | `F6A8/F6C8` | `E000[0x0093].5`, `F717.2` clear | `0x0080` | shutter value lane |
| `H'1891` | `F6A8/F6C8` | `F717.2` set | `0x00D9` | alternate/DXC-637 shutter lane |
| `H'18E7` | `F6A6/F6C6` | `E000[0x0093].5`, `F717.2` clear | `0x00A6` | shutter value lane |
| `H'18E7` | `F6A6/F6C6` | `F717.2` set | `0x00DA` | alternate/DXC-637 shutter lane |
| `H'194A` | `F6A4/F6C4` | `F731 <= 3` | `0x0080` | shared value lane |
| `H'1979` | `F6A2/F6C2` plus `F68C` scale | `F731 <= 3` | `0x0081` | scaled analog value lane |

This cluster is a strong candidate for the numeric shutter speed / clear-scan frequency side of the display. It is not yet bench-confirmed.

## Candidate Probe Frames

Readback:

```text
01 01 0F 00 00 55  ; read 0x008F
01 01 13 00 00 49  ; read 0x0093 gate/status
01 01 23 00 00 79  ; read 0x00A3
01 01 24 00 00 7E  ; read 0x00A4
01 01 25 00 00 7F  ; read 0x00A5
01 01 58 00 00 02  ; read 0x00D8
01 01 00 00 00 5A  ; read 0x0080
01 01 59 00 00 03  ; read 0x00D9
01 01 26 00 00 7C  ; read 0x00A6
01 01 5A 00 00 00  ; read 0x00DA
01 01 01 00 00 5B  ; read 0x0081
```

Potential display probes after `CONNECT: OK`:

```text
00 01 0F 00 00 54  ; clear selector 0x008F
00 01 13 80 00 C8  ; set 0x0093 high bit candidate
00 01 13 FF FF 48  ; enable all 0x0093 gates candidate
```

Use the value-lane selectors cautiously. They may represent shutter/clear-scan numeric values, but they are also part of the local control-report path, so bench probing should change one selector at a time and record LCD, shutter display, iris AUTO, and emitted report frames.