Files
BT411/scratchpad
Joe DiPrimaandClaude Fable 5 e0e9dcc292 KB: decode the pod's RGB SPLIT -- one VGA port drives THREE mono MFDs
Answering 'how do the panels split RGB into 3 monitors' from primary sources
rather than inference:

- content/GAUGE/L4GAUGE.CFG (the authentic 1996 pod config) configures each
  gauge port with a bit-plane mask AND A COLOUR CHANNEL: Comm=red,
  Mfd2=green, Heat=blue on clut2 (the upper row); Mfd1=red, Mfd3=green on
  clut1 (the lower row, blue spare); sec/radar = full rgb, rotation 270 (the
  portrait CRT).  Eng1/2/3 are the engineering-page twins on the same
  monitors, swapped in/out via reconfigure() with 'blank'.
- L4GraphicsPort::BuildSecondaryColor (L4VB16.cpp) proves the mechanism at
  T0: it walks the palette entries owned by the port's bit group and writes
  exactly ONE component (RedChannel->Red, GreenChannel->Green,
  BlueChannel->Blue, AllChannels->whole triplet); BlankColor blanks the
  group.  So one palettized framebuffer emits three independent pictures on
  the R/G/B analog lines, and the splitter feeds each line to its own mono
  monitor -- which is also what the '1280x480 horizontally spanned' MFD
  surface actually is: two VGA outputs x three channels.

Port consequence recorded: the per-panel window path (BT_POD_SURFACES) is
right for per-panel outputs but WRONG for splitter-wired glass, which needs a
channel-composite mode (three planes -> one RGB image, pure primary tints).
ExpandPlaneToBGRA already does the per-plane half.  Open: how Nick's cart is
actually wired.  Also lands the pod bring-up scratch (ssh helper, layout cfg,
launcher, firestorm repo browser).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-08-06 12:35:39 -05:00
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