MODE 9

From BeebWiki
Revision as of 20:58, 10 June 2007 by WikiStrator (talk) (Physical Colour > Actual Colour)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search
Demonstration of 'MODE 9' (BBC)

MODE 9 is the unofficial title of an ultra-low resolution screen MODE, developed by Ian Robertson and published in The Micro User magazine (November 1985, p.123). It works on the BBC Micro but not the Electron or Master, or the Archimedes (where MODE 9 is officially a 16-colour version of MODE 1).

The MODE 9 code adapts the MODE 6 screen to provide a 10 × 25 text display in 16 colours. The MOS does not allow complete support of this MODE and some bugs can be seen: for instance, text windows do not work correctly.

'MODE 9'
Type Bitmapped, text only ('ASCII')
Resolution Text 10 × 25 characters
Graphics n/a
Character size 8 × 10 pixels, top 8 lines user definable
Pixel aspect 4:1 (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 8192 bytes
on screen 8000 bytes
Address range Model B etc. &6000..&7FFF
Configuration Video ULA control register &80
Video ULA palette register file &07 &16 &25 &34
&43 &52 &61 &70
&8F &9E &AD &BC
&CB &DA &E9 &F8
CRTC register file &3F &28 &31 &24
&1E &02 &19 &1B
&01 &09 &67 &09
(from table in MOS 1.20 at &C492..&C49D)

-- beardo 12:52, 20 September 2006 (BST)