Difference between revisions of "MODE 8"
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[[Image:MODE 8 (BBC) demonstration.gif|right|Demonstration of 'MODE 8' (BBC)]] | [[Image:MODE 8 (BBC) demonstration.gif|right|Demonstration of 'MODE 8' (BBC)]] | ||
'''MODE 8''' is a high-resolution screen [[MODE]], selectable with the *MODE | '''MODE 8''' is a high-resolution screen [[MODE]], selectable with the *MODE | ||
| − | command or the NewModes sideways ROM module, that replicates the functionality of | + | command or the NewModes sideways ROM module, that replicates the functionality |
| − | the native RISC OS MODE 8.<ref name="newmodes">[http://mdfs.net/Apps/Graphics/NewModes/ NewModes]</ref> | + | of the native RISC OS MODE 8.<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, | + | The MODE 8 code adapts the [[MODE 1]] screen to provide a 4-colour version |
| − | 80 × 32 characters in 4 colours. It does this by redefining the character set | + | of MODE 0, 80 × 32 characters in 4 colours. It does this by redefining |
| − | to provide thin characters. | + | the character set to provide thin characters. |
{| class="wikitable" style="text-align:left" | {| class="wikitable" style="text-align:left" | ||
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==MODE 8 - 10x32x16== | ==MODE 8 - 10x32x16== | ||
[[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 also the unofficial title of an ultra-low resolution screen [[MODE]], | + | '''MODE 8''' is also the unofficial title of an ultra-low resolution screen |
| − | a program for which appears on page 383 of | + | [[MODE]], a program for which appears on page 383 of |
| − | ''The Advanced User Guide for the BBC Microcomputer'' (Bray ''et al.'', 1983) | + | ''The Advanced User Guide for the BBC Microcomputer'' (Bray ''et al.'', |
| − | Another program, attributed to Ian Robertson, was published in ''The Micro User'' | + | 1983) Another program, attributed to Ian Robertson, was published in ''The |
| − | magazine (November 1985, p.123). It works on the BBC and Master but not the Electron, | + | Micro User'' magazine (November 1985, p.123). It works on the BBC and Master |
| − | or the Archimedes/RISC OS (where MODE 8 is the official the 4-colour version of [[MODE 0]]). | + | but not the Electron, or the Archimedes/RISC OS (where MODE 8 is the |
| + | official the 4-colour version of [[MODE 0]]). | ||
| − | The MODE 8 code modifies the [[MODE 5]] screen to provide a 80 × 256 display in 16 | + | The MODE 8 code modifies the [[MODE 5]] screen to provide a 80 × 256 |
| − | colours. The MOS does not allow complete support of this MODE and some bugs can be seen: | + | display in 16 colours. The MOS does not allow complete support of this MODE |
| − | for instance, graphics drawn off the right-hand edge of the screen wrap around to the left, | + | and some bugs can be seen: for instance, graphics drawn off the right-hand |
| − | shifted down one text row; and [[VDU 28|text windows]] do not work correctly. | + | edge of the screen wrap around to the left, shifted down one text row; and |
| + | [[VDU 28|text windows]] do not work correctly. | ||
{| class="wikitable" style="text-align:left" | {| class="wikitable" style="text-align:left" | ||
Revision as of 13:28, 17 October 2020
MODE 8 - 80x32x4
_demonstration.gif)
MODE 8 is a high-resolution screen MODE, selectable with the *MODE command or the NewModes sideways ROM module, that replicates the functionality of the native RISC OS MODE 8.[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.
| 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 8 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.
MODE 8 - 10x32x16
MODE 8 is also 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 and Master but not the Electron, or the Archimedes/RISC OS (where MODE 8 is the official the 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.
| 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) | |
MODE 8 can be created manually with the following code running in the I/O processor.
BASIC: MODE 5 :REM Base MODE ?&30A=9 :REM Characters per line ?&34F=32 :REM Bytes per character ?&360=15 :REM Number of colours ?&361=1 :REM Pixels per byte ?&362=&AA :REM Pixel left mask ?&363=&55 :REM Pixel right mask VDU 20 :REM Reset palette *FX154,224 6502: LDA #22:JSR OSWRCH LDA #05:JSR OSWRCH \ Base MODE LDA #&09:STA &30A \ Characters per line LDA #&20:STA &34F \ Byte per character LDA #&0F:STA &360 \ Number of colours LDA #&01:STA &361 \ Pixels per byte LDA #&AA:STA &362 \ Pixel left mask LDA #&55:STA &363 \ Pixel right mask LDA #20:JSR OSWRCH \ Reset palette LDA #154:LDX #224:JSR OSBYTE \ Cursor width
See Also
References
| Screen display MODEs |
|---|
|
MODE 0 | MODE 1 | MODE 2 | MODE 3 | MODE 4 | MODE 5 | MODE 6 | MODE 7 |
Jgharston (talk) 17:25, 12 October 2016 (UTC) beardo 01:39, 13 December 2006 (GMT)
