MODE 2

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"The Prison" (from Doctor Who: The First Adventure, BBC Soft, 1983)
Exile (Superior, 1989) in square-screen mode

MODE 2 is a low-resolution screen MODE, introduced on the BBC Micro Model B and supported by the entire BBC series including the Archimedes. It allows colour graphics to be shown but leaves only 9 KB for programs -- even less if a disc interface or Econet is fitted.

MODE 2 is the only official MODE to offer 4 bits per pixel. This was usually used to display full colour graphics; several applications (including "Island" and "Planets" from the Acorn Electron Introductory Cassette) used it for cyclic animations by reprogramming the palette several times a second. The MOS makes this convenient by offering extended paint options in GCOL and commands to redefine the palette.

MODE 2
Type Graphical ('ASCII')
Resolution Text 20 × 32 characters
Graphics 160 × 256 pixels
Character size 8 × 8 pixels, user definable
Pixel aspect 2:1 (wide)
Bits per pixel 4
Default palette Logical colour Actual colour
0 0 (black)
1 1 (red)
2 2 (green)
3 3 (yellow)
4 4 (blue)
5 5 (magenta)
6 6 (cyan)
7 7 (white)
8 8 (flashing black/white)
9 9 (flashing red/cyan)
10 10 (flashing green/magenta)
11 11 (flashing yellow/blue)
12 12 (flashing blue/yellow)
13 13 (flashing magenta/green)
14 14 (flashing cyan/red)
15 15 (flashing white/black)
Memory allocated 20480 bytes
on screen 20480 bytes
Address range Model B etc. &3000..&7FFF
Configuration Video ULA control register &F4
Video ULA palette register file &07 &16 &25 &34
&43 &52 &61 &70
&8F &9E &AD &BC
&CB &DA &E9 &F8
CRTC register file &7F &50 &62 &28
&26 &00 &20 &22
&01 &07 &67 &08
(from table in MOS 1.20 at &C46E..&C479)
Screen display MODEs

MODE 0 | MODE 1 | MODE 2 | MODE 3 | MODE 4 | MODE 5 | MODE 6 | MODE 7
MODE 8 | MODE 9 | MODE 10 | MODE 11 | MODE 12 | MODE 13 | MODE 14
MODE &60 | MODE &61 | MODE &62 | MODE &63 | MODE &64 | MODE &65 | MODE &66 | MODE &67
MODE &68 | MODE &69 | MODE &6A | MODE &6B | MODE &6C | MODE &6D | MODE &6E | MODE &6F
MODE | VDU 22

-- beardo 14:11, 16 September 2006 (BST)