Difference between revisions of "MODE 8"

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[[Category:Display]]
 
[[Image:MODE 8 BBC demonstration.png|right|Demonstration of 'MODE 8' (BBC)]]
 
[[Image:MODE 8 BBC demonstration.png|right|Demonstration of 'MODE 8' (BBC)]]
 
'''MODE 8''' is the unofficial title of an ultra-low resolution screen [[MODE]], a program for which appears on page 383 of ''The Advanced User Guide for the BBC Microcomputer'' (Bray ''et al.'', 1983?)  Another program, attributed to Ian Robertson, was 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 8 is officially a 4-colour version of [[MODE 0]]).
 
'''MODE 8''' is the unofficial title of an ultra-low resolution screen [[MODE]], a program for which appears on page 383 of ''The Advanced User Guide for the BBC Microcomputer'' (Bray ''et al.'', 1983?)  Another program, attributed to Ian Robertson, was 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 8 is officially a 4-colour version of [[MODE 0]]).
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-- [[User:Beardo|beardo]] 01:39, 13 December 2006 (GMT)
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[[Image:MODE 8 (BBC) demonstration.gif|right|Demonstration of 'MODE 8' (BBC)]]
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[[Category:Display]]
+
'''MODE 8''' is also the unofficial title of a high-resolution screen [[MODE]],
 +
selectable with the *MODE command or the NewModes sideways ROM module.<ref
 +
name="newmodes">[http://mdfs.net/Apps/Graphics/NewModes/ NewModes]</ref>
 +
 
 +
The MODE 8 code adapts the [[MODE 1]] screen to provide a 4-colour version of
 +
MODE 0, 80 &times; 32 characters in 4 colours. It does this by redefining the
 +
character set to provide thin characters.
 +
 
 +
{| class="wikitable" style="text-align:left"
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|+'MODE 8'
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| Type
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| colspan="2" | Bitmapped
 +
|- style="vertical-align:top"
 +
| rowspan="2" | Resolution
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| Text
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| 80 &times; 32 characters
 +
|- style="vertical-align:top"
 +
| Graphics
 +
| 160 &times; 256
 +
|- style="vertical-align:top"
 +
| Character size
 +
| colspan="2" | 4 &times; 8 pixels
 +
|- style="vertical-align:top"
 +
| Pixel aspect
 +
| colspan="2" | 1:2 (tall)
 +
|- style="vertical-align:top"
 +
| Bits per pixel
 +
| 2
 +
|- style="vertical-align:top"
 +
| rowspan="5" | Default palette
 +
! Logical colour
 +
! Actual colour
 +
|- style="vertical-align:top"
 +
| 0
 +
| 0 (black)
 +
|- style="vertical-align:top"
 +
| 1
 +
| 1 (red)
 +
|- style="vertical-align:top"
 +
| 2
 +
| 3 (yellow)
 +
|- style="vertical-align:top"
 +
| 3
 +
| 7 (white)
 +
|- style="vertical-align:top"
 +
| rowspan="2" | Memory
 +
| allocated
 +
| 20480 bytes
 +
|- style="vertical-align:top"
 +
| on screen
 +
| 20480 bytes
 +
|- style="vertical-align:top"
 +
| rowspan="1" | Address range
 +
| Model B ''etc.''
 +
| &3000..&7FFF
 +
|- style="vertical-align:top"
 +
| rowspan="3" | Configuration
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| [[Video ULA]] control register
 +
| &98
 +
|- style="vertical-align:top"
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| Video ULA palette register file
 +
| &07 &17 &26 &36<br> &47 &57 &66 &76<br> &84 &94 &A0 &B0<br> &C4 &D4 &E0 &F0
 +
|- style="vertical-align:top"
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| [[CRTC]] register file
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| &3F &28 &31 &24<br> &26 &00 &20 &22<br> &01 &07 &67 &08
 +
|}
 +
 
 +
MODE 9 can be created manually with the following code running in the I/O
 +
processor.
 +
 
 +
    BASIC:
 +
    MODE 1    :REM Base MODE
 +
    ?&30A=79  :REM Characters per line
 +
    ?&34F=8    :REM Bytes per character
 +
    *FX154,152
 +
   
 +
    6502:
 +
    LDA #22:JSR OSWRCH
 +
    LDA #01:JSR OSWRCH          \ Base MODE
 +
    LDA #&4F:STA &30A            \ Characters per line
 +
    LDA #&08:STA &34F            \ Byte per character
 +
    LDA #154:LDX #152:JSR OSBYTE \ Cursor width
 +
 
 +
The character set needs to be redefined to be four pixels wide, such as with
 +
the one used with [http://mdfs.net/Apps/Graphics/NewModes/ NewModes].
 +
 
 +
==See Also==
 +
* [http://mdfs.net/Apps/Graphics/NewModes/ NewModes]
 +
 
 +
 
 +
 
 +
--
 +
[[User:Jgharston|Jgharston]] ([[User talk:Jgharston|talk]]) 17:25, 12 October 2016 (UTC)
 +
[[User:Beardo|beardo]] 01:39, 13 December 2006 (GMT)

Revision as of 18:25, 12 October 2016

Demonstration of 'MODE 8' (BBC)

MODE 8 is the unofficial title of an ultra-low resolution screen MODE, a program for which appears on page 383 of The Advanced User Guide for the BBC Microcomputer (Bray et al., 1983?) Another program, attributed to Ian Robertson, was 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 8 is officially a 4-colour version of MODE 0).

The MODE 8 code modifies the MODE 5 screen to provide a 80 × 256 display in 16 colours. The MOS does not allow complete support of this MODE and some bugs can be seen: for instance, graphics drawn off the right-hand edge of the screen wrap around to the left, shifted down one text row; and text windows do not work correctly.

'MODE 8'
Type Graphical ('ASCII')
Resolution Text 10 × 32 characters
Graphics 80 × 256 pixels
Character size 8 × 8 pixels, 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 10240 bytes
on screen 10240 bytes
Address range Model B etc. &5800..&7FFF
Configuration Video ULA control register &E0
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
&26 &00 &20 &22
&01 &07 &67 &08
(from table in MOS 1.20 at &C486..&C491)
Demonstration of 'MODE 8' (BBC)

MODE 8 is also the unofficial title of a high-resolution screen MODE, selectable with the *MODE command or the NewModes sideways ROM module.[1]

The MODE 8 code adapts the MODE 1 screen to provide a 4-colour version of MODE 0, 80 × 32 characters in 4 colours. It does this by redefining the character set to provide thin characters.

'MODE 8'
Type Bitmapped
Resolution Text 80 × 32 characters
Graphics 160 × 256
Character size 4 × 8 pixels
Pixel aspect 1:2 (tall)
Bits per pixel 2
Default palette Logical colour Actual colour
0 0 (black)
1 1 (red)
2 3 (yellow)
3 7 (white)
Memory allocated 20480 bytes
on screen 20480 bytes
Address range Model B etc. &3000..&7FFF
Configuration Video ULA control register &98
Video ULA palette register file &07 &17 &26 &36
&47 &57 &66 &76
&84 &94 &A0 &B0
&C4 &D4 &E0 &F0
CRTC register file &3F &28 &31 &24
&26 &00 &20 &22
&01 &07 &67 &08

MODE 9 can be created manually with the following code running in the I/O processor. 

   BASIC:
   MODE 1     :REM Base MODE
   ?&30A=79   :REM Characters per line
   ?&34F=8    :REM Bytes per character
   *FX154,152
   
   6502:
   LDA #22:JSR OSWRCH
   LDA #01:JSR OSWRCH           \ Base MODE
   LDA #&4F:STA &30A            \ Characters per line
   LDA #&08:STA &34F            \ Byte per character
   LDA #154:LDX #152:JSR OSBYTE \ Cursor width

The character set needs to be redefined to be four pixels wide, such as with the one used with NewModes.

See Also


-- Jgharston (talk) 17:25, 12 October 2016 (UTC)

beardo 01:39, 13 December 2006 (GMT)
  1. ↑ NewModes
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