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120 lines
5.5 KiB
HTML
120 lines
5.5 KiB
HTML
<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
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"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" lang="en-GB" xml:lang="en-GB">
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<head>
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<meta http-equiv="content-type"
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content="application/xhtml+xml;charset=UTF-8" />
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<title>Bedstead – MODE 7 for the 21st century</title>
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<link rel="stylesheet" href="bedstead.css" type="text/css" />
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</head>
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<body>
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<h1><img alt="Bedstead" src="title.png"/></h1>
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<p>Bedstead is a family of outline fonts based on the characters
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produced by the
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Mullard SAA5050 series of Teletext Character Generators. The
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SAA5050 is familiar to those of a certain age as the chip that
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produced the <code>MODE 7</code> display on the BBC
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Microcomputer. It generates characters from a 5 × 9 pixel
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matrix, smoothing diagonal lines to produce an interlaced 10 ×
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18 matrix for each character. Bedstead extends that algorithm to
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continuity, converting a 5 × 9 pixel grid into an outline with
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smooth diagonals.</p>
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<p>Bedstead includes all the character designs from the SAA5050
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and its various sister chips, including Cyrillic and Hebrew
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alphabets. It also has a large number of custom-designed glyphs,
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all of them of course based on the same 5 × 9 pixel grid.</p>
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<p><img alt="[ A sample of Bedstead's characters ]" src="sample.png"/></p>
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<p>Bedstead is available in six widths. The standard version of
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Bedstead is based on a square pixel grid. This is good for
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displays with square pixels, but not entirely faithful to the
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SAA5050. There is a second version, Bedstead Extended, that
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more accurately reflects the character shapes generated by an
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SAA5050 driving a 576i display.</p>
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<p>To simulate teletext double-height mode, Bedstead and
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Bedstead Extended each has a half-width version, Bedstead
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Ultra Condensed and Bedstead Extra Condensed respectively.
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Bedstead Condensed and Bedstead Semi Condensed provide intermediate
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widths.</p>
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<p><img alt="[ Various widths of Bedstead ]" src="extended.png"/></p>
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<p>The outline version of Bedstead is generated by an ISO C program
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which emits a Spline Font Database file for use with
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<a href="http://fontforge.github.io/">FontForge</a>, which
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can convert it into most reasonable font formats.</p>
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<h2>Mosaic Graphics</h2>
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<p>Bedstead includes all of the teletext mosaic graphics
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characters available from the SAA5050. Since these are not
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encoded in Unicode, Bedstead makes them available in the Private
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Use area between U+EE00 and U+EE7F, in the same arrangement as
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is used by
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<a href="http://zapping.sourceforge.net/ZVBI/">ZVBI</a>.</p>
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<h2>Copyright</h2>
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<p>The program that generates Bedstead and all of the
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newly-designed glyphs have been released into the public domain.</p>
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<p>
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<a rel="license"
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href="https://creativecommons.org/publicdomain/zero/1.0/">
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<img src="https://i.creativecommons.org/p/zero/1.0/88x31.png"
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style="border-style: none;" alt="CC0" />
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</a>
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</p>
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<p>I believe that the original SAA5050 bitmap font is essentially
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in the public domain in the United Kingdom as a result of
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<a href="http://www.legislation.gov.uk/id/ukpga/1988/48/section/55"
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>Section 55 of the Copyright, Designs and Patents Act 1988</a>
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as applied by
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<a href="http://www.legislation.gov.uk/id/ukpga/1988/48/schedule/1/paragraph/14/5"
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>subparagraph 14(5) of Schedule 1</a>. I’m not a lawyer, though,
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so this may well be wrong.
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</p>
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<h2>Downloads</h2>
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<ul>
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<li><a href="bedstead-002.000.zip"><code>bedstead-002.000.zip</code></a>
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– Full source and binary distribution containing everything
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below and more.</li>
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<li><a href="bedstead.c"><code>bedstead.c</code></a> – The C
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program that generates the font.</li>
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<li>Finished OpenType fonts:
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<ul>
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<li><a href="bedstead.otf"><code>bedstead.otf</code></a> –
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Bedstead</li>
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<li><a href="bedstead-extended.otf"><code>bedstead-extended.otf</code></a>
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– Bedstead Extended</li>
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<li><a href="bedstead-semicondensed.otf"><code>bedstead-semicondensed.otf</code></a>
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– Bedstead Semi Condensed</li>
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<li><a href="bedstead-condensed.otf"><code>bedstead-condensed.otf</code></a>
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– Bedstead Condensed</li>
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<li><a href="bedstead-extracondensed.otf"><code>bedstead-extracondensed.otf</code></a>
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– Bedstead Extra Condensed</li>
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<li><a href="bedstead-ultracondensed.otf"><code>bedstead-ultracondensed.otf</code></a>
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– Bedstead Ultra Condensed</li>
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</ul>
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</li>
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<li><a href="bedstead-10.bdf"><code>bedstead-10.bdf</code></a>,
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<a href="bedstead-20.bdf"><code>bedstead-20.bdf</code></a> –
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Bitmap versions at 10 and 20 pixels high.</li>
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<li><a href="bedstead-10-df.png"><code>bedstead-10-df.png</code></a>,
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<a href="bedstead-20-df.png"><code>bedstead-20-df.png</code></a>
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– 10-pixel and 20-pixel tilesets for use with
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<a href="http://www.bay12games.com/dwarves/">Dwarf Fortress</a>.</li>
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<li><a href="bedstead-complement.pdf"><code>bedstead-complement.pdf</code></a>
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– A complete catalogue of glyphs in PDF.</li>
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</ul>
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<p>The code to generate Bedstead is held in
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<a href="http://bazaar-vcs.org/">Bazaar</a>.
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You can get your own copy by running</p>
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<blockquote>
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<p><kbd>bzr branch http://bjh21.me.uk/bedstead/</kbd></p>
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</blockquote>
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</body>
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</html>
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