http://beebwiki.mdfs.net/index.php?title=MODE_7&feed=atom&action=historyMODE 7 - Revision history2024-03-28T11:13:09ZRevision history for this page on the wikiMediaWiki 1.30.0-rc.0http://beebwiki.mdfs.net/index.php?title=MODE_7&diff=3727&oldid=prevJgharston: Slight tweeks.2020-10-17T12:25:52Z<p>Slight tweeks.</p>
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<td colspan="2" style="background-color: white; color:black; text-align: center;">Revision as of 12:25, 17 October 2020</td>
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<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>[[Image:Space Invaders gameplay screenshot.png|right|''Space Invaders'' (Acornsoft, 1982)]]</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>[[Image:Space Invaders gameplay screenshot.png|right|''Space Invaders'' (Acornsoft, 1982)]]</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>[[Image:Teletext_Engineering_Test_Page.png|right|Teletext test page]]</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>[[Image:Teletext_Engineering_Test_Page.png|right|Teletext test page]]</div></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>'''MODE 7''' is a medium-resolution screen [[MODE]], introduced on the BBC Micro Model A and supported by the entire BBC series including the Archimedes and RISC OS systems. It provides a 40 &times; 25 [[Teletext]] character display for terminal applications, such as Teletext receivers and viewdata. It also uses one-eighth of the memory of [[MODE 6]].</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>'''MODE 7''' is a medium-resolution screen [[MODE]], introduced on the BBC</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Micro Model A and supported by the entire BBC series including the</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Archimedes and RISC OS systems. It provides a 40 &times; 25 [[Teletext]]</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>character display for terminal applications, such as Teletext receivers and</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>viewdata. It also uses one-eighth of the memory of [[MODE 6]].</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The behaviour of Teletext is different from the bitmapped MODEs; the [[5050|SAA 5050]] chip is driven by '[[ASCII]]' (-variant) bytes stored directly in memory. The text colour is changed and graphics are enabled line-by-line, using control codes that occupy a character cell. Several aspects of the display are governed by the SAA 5050; interlace is forced on, and text rows must be 20 scanlines deep as the chip contains its own line counter.</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The behaviour of Teletext is different from the bitmapped MODEs; the</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>[[5050|SAA 5050]] chip is driven by '[[ASCII]]' (-variant) bytes stored</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>directly in memory. The text colour is changed and graphics are enabled</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>line-by-line, using control codes that occupy a character cell. Several</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>aspects of the display are governed by the SAA 5050; interlace is forced on,</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>and text rows must be 20 scanlines deep as the chip contains its own line</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>counter.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>As the philosophy is different to the bitmapped MODEs, the built-in firmware does not support the Teletext features. Graphics functions (all [[PLOT]] commands, [[CLG]], [[GCOL]], [[VDU 5|cursor coupling]], the [[VDU 29|graphics origin]] and [[VDU 24|graphics window]]) have no visible effect; furthermore the [[COLOUR]] statement and [[VDU 19]] do not work in MODE 7.</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>As the philosophy is different to the bitmapped MODEs, the built-in firmware</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>does not support the Teletext features. Graphics functions (all [[PLOT]]</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>commands, [[CLG]], [[GCOL]], [[VDU 5|cursor coupling]], the</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>[[VDU 29|graphics origin]] and [[VDU 24|graphics window]]) have no visible</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>effect; furthermore the [[COLOUR]] statement and [[VDU 19]] do not work in</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>MODE 7.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The Teletext colours and graphics are enabled by user programs putting control codes on the screen themselves; however it is still all done through the VDU routines ([[PRINT]], [[VDU]], or the [[OSWRCH]] call). Acorn have successfully encouraged programs to use the standard API so that future Acorn products will be compatible. OSWRCH takes its own [[VDU#VDU commands|control codes]] of course, and translates three of the printable ASCII characters to their Teletext equivalents; this is why graphics codes must have bit 7 set even though the SAA 5050 is a 7-bit device.</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The Teletext colours and graphics are enabled by user programs putting</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>control codes on the screen themselves; however it is still all done through</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>the VDU routines ([[PRINT]], [[VDU]], or the [[OSWRCH]] call). Acorn have</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>successfully encouraged programs to use the standard API so that future</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Acorn products will be compatible. OSWRCH takes its own</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>[[VDU#VDU commands|control codes]] of course, and translates three of the</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>printable ASCII characters to their Teletext equivalents; this is why</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>graphics codes must have bit 7 set even though the SAA 5050 is a 7-bit</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>device.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The screen of MODE 7 is shifted one character to the right compared to MODE 6; this is a feature of the SAA 5050, and the [[Video ULA]] accommodates it with a matching shift of the cursor. When using coloured backgrounds the display can be better centred with VDU 23;2,51;0;0;0.</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The screen of MODE 7 is shifted one character to the right compared to MODE</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>6; this is a feature of the SAA 5050, and the [[Video ULA]] accommodates it</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>with a matching shift of the cursor. When using coloured backgrounds the</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>display can be better centred with VDU 23;2,51;0;0;0.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Although 24 bytes of display memory are off screen at any one time, these are not available to programs. If used unofficially they are prone to corruption, unless the program guarantees that no [[hardware scrolling]] will occur. When hardware scrolling moves the start of display memory, the mapped area will extend right up to &7FFF and wrap around to &7C00.</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Although 24 bytes of display memory are off screen at any one time, these</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>are not available to programs. If used unofficially they are prone to</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>corruption, unless the program guarantees that no [[hardware scrolling]]</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>will occur. When hardware scrolling moves the start of display memory, the</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>mapped area will extend right up to &7FFF and wrap around to &7C00.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Due to the high display quality and tiny memory footprint MODE 7 has proved popular on the BBC Micro. It is the mode of choice for all memory-intensive programs that do not require graphics display. It is also used for information screens in some games before the gameplay starts.</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Due to the high display quality and tiny memory footprint MODE 7 has proved</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>popular on the BBC Micro. It is the mode of choice for all memory-intensive</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>programs that do not require graphics display. It is also used for</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>information screens in some games before the gameplay starts.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The Electron has no Teletext hardware and so the MOS substitutes MODE 7 with MODE 6, but provides no Teletext emulation. RISC OS does offer full Teletext emulation with coarser character outlines, using one of the colour bitmap MODEs.</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The Electron has no Teletext hardware and so the MOS substitutes MODE 7 with</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>MODE 6, but provides no Teletext emulation. RISC OS does offer full Teletext</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>emulation with coarser character outlines, using one of the colour bitmap</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>MODEs.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>{| class="wikitable" style="text-align:left"</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>{| class="wikitable" style="text-align:left"</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>|+MODE 7</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>|+MODE 7</div></td></tr>
</table>Jgharstonhttp://beebwiki.mdfs.net/index.php?title=MODE_7&diff=2918&oldid=prevJgharston at 22:43, 12 October 20162016-10-12T22:43:53Z<p></p>
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<td colspan="2" style="background-color: white; color:black; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: white; color:black; text-align: center;">Revision as of 22:43, 12 October 2016</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l3" >Line 3:</td>
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<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>[[Image:Space Invaders gameplay screenshot.png|right|''Space Invaders'' (Acornsoft, 1982)]]</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>[[Image:Space Invaders gameplay screenshot.png|right|''Space Invaders'' (Acornsoft, 1982)]]</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>[[Image:Teletext_Engineering_Test_Page.png|right|Teletext test page]]</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>[[Image:Teletext_Engineering_Test_Page.png|right|Teletext test page]]</div></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>'''MODE 7''' is a medium-resolution screen [[MODE]], introduced on the BBC Micro Model A and supported by the entire BBC series including the Archimedes. <del class="diffchange diffchange-inline"> </del>It provides a 40 &times; 25 [[Teletext]] character display for terminal applications, such as Teletext receivers and viewdata. <del class="diffchange diffchange-inline"> </del>It also uses one-eighth of the memory of [[MODE 6]].</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>'''MODE 7''' is a medium-resolution screen [[MODE]], introduced on the BBC Micro Model A and supported by the entire BBC series including the Archimedes <ins class="diffchange diffchange-inline">and RISC OS systems</ins>. It provides a 40 &times; 25 [[Teletext]] character display for terminal applications, such as Teletext receivers and viewdata. It also uses one-eighth of the memory of [[MODE 6]].</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The behaviour of Teletext is different from the bitmapped MODEs; the [[5050|SAA 5050]] chip is driven by '[[ASCII]]' (-variant) bytes stored directly in memory. <del class="diffchange diffchange-inline"> </del>The text colour is changed and graphics are enabled line-by-line, using control codes that occupy a character cell. <del class="diffchange diffchange-inline"> </del>Several aspects of the display are governed by the SAA 5050; interlace is forced on, and text rows must be 20 scanlines deep as the chip contains its own line counter.</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The behaviour of Teletext is different from the bitmapped MODEs; the [[5050|SAA 5050]] chip is driven by '[[ASCII]]' (-variant) bytes stored directly in memory. The text colour is changed and graphics are enabled line-by-line, using control codes that occupy a character cell. Several aspects of the display are governed by the SAA 5050; interlace is forced on, and text rows must be 20 scanlines deep as the chip contains its own line counter.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>As the philosophy is different to the bitmapped MODEs, the built-in firmware does not support the Teletext features. <del class="diffchange diffchange-inline"> </del>Graphics functions (all [[PLOT]] commands, [[CLG]], [[GCOL]], [[VDU 5|cursor coupling]], the [[VDU 29|graphics origin]] and [[VDU 24|graphics window]]) have no visible effect; furthermore the [[COLOUR]] statement and [[VDU 19]] do not work in MODE 7.</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>As the philosophy is different to the bitmapped MODEs, the built-in firmware does not support the Teletext features. Graphics functions (all [[PLOT]] commands, [[CLG]], [[GCOL]], [[VDU 5|cursor coupling]], the [[VDU 29|graphics origin]] and [[VDU 24|graphics window]]) have no visible effect; furthermore the [[COLOUR]] statement and [[VDU 19]] do not work in MODE 7.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The Teletext colours and graphics are enabled by user programs putting control codes on the screen themselves; however it is still all done through the VDU routines ([[PRINT]], [[VDU]], or the [[OSWRCH]] call). <del class="diffchange diffchange-inline"> </del>Acorn have successfully encouraged programs to use the standard API so that future Acorn products will be compatible. <del class="diffchange diffchange-inline"> </del>OSWRCH takes its own [[VDU#VDU commands|control codes]] of course, and translates three of the printable ASCII characters to their Teletext equivalents; this is why graphics codes must have bit 7 set even though the SAA 5050 is a 7-bit device.</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The Teletext colours and graphics are enabled by user programs putting control codes on the screen themselves; however it is still all done through the VDU routines ([[PRINT]], [[VDU]], or the [[OSWRCH]] call). Acorn have successfully encouraged programs to use the standard API so that future Acorn products will be compatible. OSWRCH takes its own [[VDU#VDU commands|control codes]] of course, and translates three of the printable ASCII characters to their Teletext equivalents; this is why graphics codes must have bit 7 set even though the SAA 5050 is a 7-bit device.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The screen of MODE 7 is shifted one character to the right compared to MODE 6; this is a feature of the SAA 5050, and the [[Video ULA]] accommodates it with a matching shift of the cursor. <del class="diffchange diffchange-inline">The </del>display can be better centred with VDU 23;2,51;0;0;0.</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The screen of MODE 7 is shifted one character to the right compared to MODE 6; this is a feature of the SAA 5050, and the [[Video ULA]] accommodates it with a matching shift of the cursor. <ins class="diffchange diffchange-inline">When using coloured backgrounds the </ins>display can be better centred with VDU 23;2,51;0;0;0.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Although 24 bytes of display memory are off screen at any one time, these are not available to programs. <del class="diffchange diffchange-inline"> </del>If used unofficially they are prone to corruption, unless the program guarantees that no [[hardware scrolling]] will occur. <del class="diffchange diffchange-inline"> </del>When hardware scrolling moves the start of display memory, the mapped area will extend right up to &7FFF and wrap around to &7C00.</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Although 24 bytes of display memory are off screen at any one time, these are not available to programs. If used unofficially they are prone to corruption, unless the program guarantees that no [[hardware scrolling]] will occur. When hardware scrolling moves the start of display memory, the mapped area will extend right up to &7FFF and wrap around to &7C00.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Due to the high display quality and tiny memory footprint MODE 7 has proved popular on the BBC Micro. <del class="diffchange diffchange-inline"> </del>It is the mode of choice for all memory-intensive programs that do not require graphics display. <del class="diffchange diffchange-inline"> </del>It is also used for information screens in some games before the gameplay starts.</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Due to the high display quality and tiny memory footprint MODE 7 has proved popular on the BBC Micro. It is the mode of choice for all memory-intensive programs that do not require graphics display. It is also used for information screens in some games before the gameplay starts.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The Electron has no Teletext hardware and so the MOS substitutes MODE 7 with MODE 6, but provides no Teletext emulation. <del class="diffchange diffchange-inline"> </del>RISC OS does offer full Teletext emulation with coarser character outlines, using one of the colour bitmap MODEs.</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The Electron has no Teletext hardware and so the MOS substitutes MODE 7 with MODE 6, but provides no Teletext emulation. RISC OS does offer full Teletext emulation with coarser character outlines, using one of the colour bitmap MODEs.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>{| class="wikitable" style="text-align:left"</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>{| class="wikitable" style="text-align:left"</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>|+MODE 7</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>|+MODE 7</div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>{{MODE}}</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>{{MODE}}</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>-- [[User:Beardo|beardo]] 01:06, 8 November 2007 (UTC)</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>-- [[User:Beardo|beardo]] 01:06, 8 November 2007 (UTC)</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">[[User:Jgharston|Jgharston]] ([[User talk:Jgharston|talk]]) 22:43, 12 October 2016 (UTC)</ins></div></td></tr>
</table>Jgharstonhttp://beebwiki.mdfs.net/index.php?title=MODE_7&diff=2916&oldid=prevJgharston: Added teletext test page.2016-10-12T22:32:08Z<p>Added teletext test page.</p>
<table class="diff diff-contentalign-left" data-mw="interface">
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<td colspan="2" style="background-color: white; color:black; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: white; color:black; text-align: center;">Revision as of 22:32, 12 October 2016</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l2" >Line 2:</td>
<td colspan="2" class="diff-lineno">Line 2:</td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>[[Image:Screwball intro screenshot.png|right|''Screwball'' (MRM Software, 1984)]]</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>[[Image:Screwball intro screenshot.png|right|''Screwball'' (MRM Software, 1984)]]</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>[[Image:Space Invaders gameplay screenshot.png|right|''Space Invaders'' (Acornsoft, 1982)]]</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>[[Image:Space Invaders gameplay screenshot.png|right|''Space Invaders'' (Acornsoft, 1982)]]</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">[[Image:Teletext_Engineering_Test_Page.png|right|Teletext test page]]</ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>'''MODE 7''' is a medium-resolution screen [[MODE]], introduced on the BBC Micro Model A and supported by the entire BBC series including the Archimedes.  It provides a 40 &times; 25 [[Teletext]] character display for terminal applications, such as Teletext receivers and viewdata.  It also uses one-eighth of the memory of [[MODE 6]].</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>'''MODE 7''' is a medium-resolution screen [[MODE]], introduced on the BBC Micro Model A and supported by the entire BBC series including the Archimedes.  It provides a 40 &times; 25 [[Teletext]] character display for terminal applications, such as Teletext receivers and viewdata.  It also uses one-eighth of the memory of [[MODE 6]].</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
</table>Jgharstonhttp://beebwiki.mdfs.net/index.php?title=MODE_7&diff=2899&oldid=prevJgharston at 18:27, 12 October 20162016-10-12T18:27:37Z<p></p>
<table class="diff diff-contentalign-left" data-mw="interface">
<col class="diff-marker" />
<col class="diff-content" />
<col class="diff-marker" />
<col class="diff-content" />
<tr style="vertical-align: top;" lang="en">
<td colspan="2" style="background-color: white; color:black; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: white; color:black; text-align: center;">Revision as of 18:27, 12 October 2016</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l1" >Line 1:</td>
<td colspan="2" class="diff-lineno">Line 1:</td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">[[Category:Display]]</ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>[[Image:Screwball intro screenshot.png|right|''Screwball'' (MRM Software, 1984)]]</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>[[Image:Screwball intro screenshot.png|right|''Screwball'' (MRM Software, 1984)]]</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>[[Image:Space Invaders gameplay screenshot.png|right|''Space Invaders'' (Acornsoft, 1982)]]</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>[[Image:Space Invaders gameplay screenshot.png|right|''Space Invaders'' (Acornsoft, 1982)]]</div></td></tr>
<tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l9" >Line 9:</td>
<td colspan="2" class="diff-lineno">Line 10:</td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>The Teletext colours and graphics are enabled by user programs putting control codes on the screen themselves; however it is still all done through the VDU routines ([[PRINT]], [[VDU]], or the [[OSWRCH]] call).  Acorn have successfully encouraged programs to use the standard API so that future Acorn products will be compatible.  OSWRCH takes its own [[VDU#VDU commands|control codes]] of course, and translates three of the printable ASCII characters to their Teletext equivalents; this is why graphics codes must have bit 7 set even though the SAA 5050 is a 7-bit device.</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>The Teletext colours and graphics are enabled by user programs putting control codes on the screen themselves; however it is still all done through the VDU routines ([[PRINT]], [[VDU]], or the [[OSWRCH]] call).  Acorn have successfully encouraged programs to use the standard API so that future Acorn products will be compatible.  OSWRCH takes its own [[VDU#VDU commands|control codes]] of course, and translates three of the printable ASCII characters to their Teletext equivalents; this is why graphics codes must have bit 7 set even though the SAA 5050 is a 7-bit device.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The screen of MODE 7 is shifted one character to the right compared to MODE 6; this is a feature of the SAA 5050, and the [[Video ULA]] accommodates it with a matching shift of the cursor.</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The screen of MODE 7 is shifted one character to the right compared to MODE 6; this is a feature of the SAA 5050, and the [[Video ULA]] accommodates it with a matching shift of the cursor<ins class="diffchange diffchange-inline">. The display can be better centred with VDU 23;2,51;0;0;0</ins>.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>Although 24 bytes of display memory are off screen at any one time, these are not available to programs.  If used unofficially they are prone to corruption, unless the program guarantees that no [[hardware scrolling]] will occur.  When hardware scrolling moves the start of display memory, the mapped area will extend right up to &7FFF and wrap around to &7C00.</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>Although 24 bytes of display memory are off screen at any one time, these are not available to programs.  If used unofficially they are prone to corruption, unless the program guarantees that no [[hardware scrolling]] will occur.  When hardware scrolling moves the start of display memory, the mapped area will extend right up to &7FFF and wrap around to &7C00.</div></td></tr>
<tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l59" >Line 59:</td>
<td colspan="2" class="diff-lineno">Line 60:</td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>|- style="vertical-align:top"</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>|- style="vertical-align:top"</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>| [[CRTC]] register file</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>| [[CRTC]] register file</div></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>| &3F &28 &33 &24<del class="diffchange diffchange-inline"><br> </del>&1E &02 &19 &1B<del class="diffchange diffchange-inline"><br> </del>&93 &12 &72 &13<br> (from table in [[MOS 1.20]] at &C49E..&C4A9)</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>| &3F &28 &33<ins class="diffchange diffchange-inline">* </ins>&24 &1E &02<ins class="diffchange diffchange-inline"><br> </ins>&19 &1B &93 &12 &72 &13<br> (from table in [[MOS 1.20]] at &C49E..&C4A9)<ins class="diffchange diffchange-inline"><br>* use &31 to centre the display better</ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>|}</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>|}</div></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div> </div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins class="diffchange diffchange-inline">{{MODE}}</ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>-- [[User:Beardo|beardo]] 01:06, 8 November 2007 (UTC)</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>-- [[User:Beardo|beardo]] 01:06, 8 November 2007 (UTC)</div></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;">[[Category:Display]]</del></div></td><td colspan="2"> </td></tr>
</table>Jgharstonhttp://beebwiki.mdfs.net/index.php?title=MODE_7&diff=1592&oldid=prevWikiSysop: 1 revision2015-03-08T18:12:43Z<p>1 revision</p>
<table class="diff diff-contentalign-left" data-mw="interface">
<tr style="vertical-align: top;" lang="en">
<td colspan="1" style="background-color: white; color:black; text-align: center;">← Older revision</td>
<td colspan="1" style="background-color: white; color:black; text-align: center;">Revision as of 18:12, 8 March 2015</td>
</tr><tr><td colspan="2" style="text-align: center;" lang="en"><div class="mw-diff-empty">(No difference)</div>
</td></tr></table>WikiSysophttp://beebwiki.mdfs.net/index.php?title=MODE_7&diff=358&oldid=prevWikiSysop: 1 revision2015-03-08T00:13:08Z<p>1 revision</p>
<table class="diff diff-contentalign-left" data-mw="interface">
<tr style="vertical-align: top;" lang="en">
<td colspan="1" style="background-color: white; color:black; text-align: center;">← Older revision</td>
<td colspan="1" style="background-color: white; color:black; text-align: center;">Revision as of 00:13, 8 March 2015</td>
</tr><tr><td colspan="2" style="text-align: center;" lang="en"><div class="mw-diff-empty">(No difference)</div>
</td></tr></table>WikiSysophttp://beebwiki.mdfs.net/index.php?title=MODE_7&diff=1591&oldid=prevWikiSysop: 1 revision2013-08-28T22:58:17Z<p>1 revision</p>
<table class="diff diff-contentalign-left" data-mw="interface">
<tr style="vertical-align: top;" lang="en">
<td colspan="1" style="background-color: white; color:black; text-align: center;">← Older revision</td>
<td colspan="1" style="background-color: white; color:black; text-align: center;">Revision as of 22:58, 28 August 2013</td>
</tr><tr><td colspan="2" style="text-align: center;" lang="en"><div class="mw-diff-empty">(No difference)</div>
</td></tr></table>WikiSysophttp://beebwiki.mdfs.net/index.php?title=MODE_7&diff=357&oldid=prevBeardo: linked control codes to VDU commands2007-11-08T01:06:53Z<p>linked control codes to VDU commands</p>
<p><b>New page</b></p><div>[[Image:Screwball intro screenshot.png|right|''Screwball'' (MRM Software, 1984)]]<br />
[[Image:Space Invaders gameplay screenshot.png|right|''Space Invaders'' (Acornsoft, 1982)]]<br />
'''MODE 7''' is a medium-resolution screen [[MODE]], introduced on the BBC Micro Model A and supported by the entire BBC series including the Archimedes. It provides a 40 &times; 25 [[Teletext]] character display for terminal applications, such as Teletext receivers and viewdata. It also uses one-eighth of the memory of [[MODE 6]].<br />
<br />
The behaviour of Teletext is different from the bitmapped MODEs; the [[5050|SAA 5050]] chip is driven by '[[ASCII]]' (-variant) bytes stored directly in memory. The text colour is changed and graphics are enabled line-by-line, using control codes that occupy a character cell. Several aspects of the display are governed by the SAA 5050; interlace is forced on, and text rows must be 20 scanlines deep as the chip contains its own line counter.<br />
<br />
As the philosophy is different to the bitmapped MODEs, the built-in firmware does not support the Teletext features. Graphics functions (all [[PLOT]] commands, [[CLG]], [[GCOL]], [[VDU 5|cursor coupling]], the [[VDU 29|graphics origin]] and [[VDU 24|graphics window]]) have no visible effect; furthermore the [[COLOUR]] statement and [[VDU 19]] do not work in MODE 7.<br />
<br />
The Teletext colours and graphics are enabled by user programs putting control codes on the screen themselves; however it is still all done through the VDU routines ([[PRINT]], [[VDU]], or the [[OSWRCH]] call). Acorn have successfully encouraged programs to use the standard API so that future Acorn products will be compatible. OSWRCH takes its own [[VDU#VDU commands|control codes]] of course, and translates three of the printable ASCII characters to their Teletext equivalents; this is why graphics codes must have bit 7 set even though the SAA 5050 is a 7-bit device.<br />
<br />
The screen of MODE 7 is shifted one character to the right compared to MODE 6; this is a feature of the SAA 5050, and the [[Video ULA]] accommodates it with a matching shift of the cursor.<br />
<br />
Although 24 bytes of display memory are off screen at any one time, these are not available to programs. If used unofficially they are prone to corruption, unless the program guarantees that no [[hardware scrolling]] will occur. When hardware scrolling moves the start of display memory, the mapped area will extend right up to &7FFF and wrap around to &7C00.<br />
<br />
Due to the high display quality and tiny memory footprint MODE 7 has proved popular on the BBC Micro. It is the mode of choice for all memory-intensive programs that do not require graphics display. It is also used for information screens in some games before the gameplay starts.<br />
<br />
The Electron has no Teletext hardware and so the MOS substitutes MODE 7 with MODE 6, but provides no Teletext emulation. RISC OS does offer full Teletext emulation with coarser character outlines, using one of the colour bitmap MODEs.<br />
{| class="wikitable" style="text-align:left"<br />
|+MODE 7<br />
| Type<br />
| colspan="2" | Teletext<br />
|- style="vertical-align:top"<br />
| rowspan="2" | Resolution<br />
| Text<br />
| 40 &times; 25 characters<br />
|- style="vertical-align:top"<br />
| Graphics<br />
| 78 &times; 75 (block graphics, user generated)<br />
|- style="vertical-align:top"<br />
| Character size<br />
| colspan="2" | 12 &times; 20 pixels, hardware defined (interpolated from 6 &times; 10 matrix)<br />
|- style="vertical-align:top"<br />
| Pixel aspect<br />
| colspan="2" | 1:1 (square)<br />
|- style="vertical-align:top"<br />
| Bits per pixel<br />
| 1<br />
|- style="vertical-align:top"<br />
| Default palette<br />
| colspan="2" | ''n/a''<br />
|- style="vertical-align:top"<br />
| rowspan="2" | Memory<br />
| allocated<br />
| 1024 bytes<br />
|- style="vertical-align:top"<br />
| on screen<br />
| 1000 bytes<br />
|- style="vertical-align:top"<br />
| rowspan="1" | Address range<br />
| Model B ''etc.''<br />
| &7C00..&7FFF<br />
|- style="vertical-align:top"<br />
| rowspan="3" | Configuration<br />
| [[Video ULA]] control register<br />
| &4B<br />
|- style="vertical-align:top"<br />
| Video ULA palette register file<br />
| ''n/a''<br />
|- style="vertical-align:top"<br />
| [[CRTC]] register file<br />
| &3F &28 &33 &24<br> &1E &02 &19 &1B<br> &93 &12 &72 &13<br> (from table in [[MOS 1.20]] at &C49E..&C4A9)<br />
|}<br />
<br />
-- [[User:Beardo|beardo]] 01:06, 8 November 2007 (UTC)<br />
[[Category:Display]]</div>Beardo