Framebuffer¶

The BE-300 LCD is modeled as a 240x320 portrait framebuffer mapped through the VRC4173 companion chip.

Display Specifications¶

Parameter	Value
Visible resolution	240 x 320 pixels
Color depth	16 bits per pixel
Main format	RGB565
Framebuffer base	PA `0x0A200000`, kseg1 `0xAA200000`
Guest stride	256 pixels, 512 bytes

The emulator stores each scanline in a 256-pixel stride and displays the first 240 visible pixels.

Video Memory Layout¶

pixel_address = 0xAA200000 + (row * 512) + (col * 2)

row ranges from 0 to 319; col ranges from 0 to 239.

Pixel Format¶

Pixels are 16-bit little-endian RGB565 values:

Bit: 15 14 13 12 11 10  9  8  7  6  5  4  3  2  1  0
      R  R  R  R  R  G  G  G  G  G  G  B  B  B  B  B

Component	Bits	Range
Red	15:11	0-31
Green	10:5	0-63
Blue	4:0	0-31

Some historical Linux paths use a 5-bit green interpretation. Current emulator documentation should prefer the source CLI over older removed flags when describing how to run those kernels.

WinCE Display Rendering¶

Windows CE renders the "Initializing..." and "Starting..." screens at runtime. The strings are not stored as ready-made bitmaps in NK.exe; display/GWE code fills scratch buffers and blits them to the framebuffer.

The OAL display dispatcher includes modes for clearing the screen and copying splash/progress buffers into the VRC4173 framebuffer aperture.

Native UI¶

The native SDL frontend reads the framebuffer backing store and can show:

LCD-only mode by default
BE-300 frame/bezel mode with --frame
scaled output with --scale 1.0 through --scale 4.0
host-rendered buzzer audio unless BE300_AUDIO=0 is set

The web and Android frontends reuse the same framebuffer copy API and frame assets.