dwt/screenshot: --real reads the 1024x2048 interleaved framebuffer and keeps the even rows 1:1; corrects the earlier doubling

dwt/notes/REAL_UNIT.md

@@ -107,3 +107,28 @@ This is a **display-fetch difference, not a CPU-emulation difference**. MAME's
 driver models a linear 1bpp framebuffer, so the emulator never shows the
 interleave; the real TMS34010 display controller is programmed for the doubled
 even field.
+
+### Correction: the framebuffer is 1024x2048, not line-doubled
+
+The earlier "the display doubles the even field" reading was wrong. A **256 KiB**
+read (2048 rows x 128 bytes) shows the 1024 image lines sitting on **even rows
+at 1:1**, with the odd rows carrying the mask. The earlier 128 KiB read held
+only the **top 512 image lines**; doubling them stretched the top half and cut
+the bottom — which is exactly the "missing left/bottom" and "line doubled"
+appearance.
+
+Correct 1:1 capture:
+
+```sh
+python3 dwt/screenshot.py --host 100.103.100.103 --real --out screen.png
+```
+
+`--real` means `--rows 0:2048 --field even` and outputs **1024x1024 with no
+resampling**. `dwt/evidence/real-unit-1to1.png` is that capture: Icon Box,
+Terminal Manager, Memory bar, and the `Ethernet Port Error - 24` box at the
+bottom — the whole screen.
+
+`--stretch 1280x1024` is only the monitor's 5:4 scaling of the 1024-wide
+framebuffer; it is **not** 1:1 and the nearest-neighbour version produces the
+uneven-pixel artefacts. Use it only for an approximate visual match, not as
+evidence.