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<html xmlns="http://www.w3.org/1999/xhtml" lang="en-GB" xml:lang="en-GB">
<head>
<!-- SPDX-License-Identifier: CC0-1.0 -->
<title>Bedstead – MODE 7 for the 21st century</title>
<link rel="stylesheet" href="bedstead.css" type="text/css" />
<link rel="icon" href="icon-16.png" type="image/png" sizes="16x16" />
<link rel="icon" href="icon-32.png" type="image/png" sizes="32x32" />
<link rel="icon" href="icon-64.png" type="image/png" sizes="64x64" />
</head>
<body>
<h1><span class="fade">Bedstead</span></h1>
<p>Bedstead is a family of outline fonts based on the characters
produced by the
Mullard SAA5050 series of Teletext Character Generators. The
SAA5050 is familiar to those of a certain age as the chip that
produced the <code>MODE 7</code> display on the BBC
Microcomputer. It generates characters from a 5 × 9 pixel
matrix, smoothing diagonal lines to produce an interlaced 10 × 18
matrix for each character. Bedstead extends that algorithm to
continuity, converting a 5 × 9 pixel grid into an outline with
smooth diagonals.</p>
<p>Bedstead includes all the character designs from the SAA5050
and its various sister chips, including Cyrillic and Hebrew
alphabets. It also has a large number of custom-designed glyphs,
all of them of course based on the same 5 × 9 pixel grid.</p>
<p class="image-sample">
<img alt="[ A sample of Bedstead’s characters ]" src="sample.png"/>
</p>
<blockquote class="text-sample" style="text-align: center;">
<div>
ABCDEFGHIJKLMNOPQRSTUVWXYZ<br/>
abcdefghijklmnopqrstuvwxyz<br/>
<span style="font-variant: small-caps">
abcdefghijklmnopqrstuvwxyz
</span><br/>
ΑΒΓΔΕΖΗΘΙΚΛΜΝΞΟΠΡΣΤΥΦΧΨΩ<br/>
αβγδεζηθικλμνξοπρσςτυφϕχψω<br/>
АБВГДЕЖЗИЙКЛМНОПРСТУФХЦЧШЩЪЫЬЭЮЯ<br/>
абвгдежзийклмнопрстуфхцчшщъыьэюя<br/>
אבגדהוזחטיכךלמםנןסעפףצץקרשת<br/>
0123456789¼½¾!?.,:;'"‘’“”()[]{}<br/>
-—+×÷<=>/\|£$¥¢¤%&*#@¶©®℗<br/>
</div>
</blockquote>
<h2>Styles</h2>
<p>Bedstead is available in six widths. The standard version of
Bedstead is based on a square pixel grid. This is good for
displays with square pixels, but not entirely faithful to the
SAA5050. There is a second version, Bedstead Extended, that
more accurately reflects the character shapes generated by an
SAA5050 driving a 576i display.</p>
<p>To simulate teletext double-height mode, Bedstead and
Bedstead Extended each has a half-width version, Bedstead
Ultra Condensed and Bedstead Extra Condensed respectively.
Bedstead Condensed and Bedstead Semi Condensed provide intermediate
widths.</p>
<p class="image-sample">
<img alt="[ Various widths of Bedstead ]" src="extended.png"/>
</p>
<blockquote class="text-sample">
<div style="display: inline-block; width: 10em;">
<div style="font-stretch: normal;">Bedstead</div>
<div style="font-size: 2em; font-stretch: ultra-condensed;">
Ultra Condensed
</div>
</div>
<div style="display: inline-block;">
<div style="font-stretch: expanded;">Extended</div>
<div style="font-size: 2em; font-stretch: extra-condensed;">
Extra Condensed
</div>
</div>
</blockquote>
<p>Each width also comes in a bold variant based on the idea of a
variant SAA5050 that could advance its rising edges by one output
pixel, thickening the vertical and diagonal lines.</p>
<h2>Mosaic Graphics</h2>
<p>Bedstead includes all of the teletext mosaic graphics
characters available from the SAA5050. These are encoded
at the standard code points defined by Unicode.
These characters are also encoded in the Private
Use area between U+EE00 and U+EE7F, in the same arrangement as
is used by
<a href="http://zapping.sourceforge.net/ZVBI/">ZVBI</a>.</p>
<blockquote>
<pre>🬰🬰🬒🬰🬰🬒🬰🬰🬒🬰🬰🬒🬰🬰🬒🬰🬰🬒🬰🬰🬒🬰🬰🬒
▌🬚🬄▌🬚🬄▌🬚🬄▌🬚🬄▌🬚🬄▌🬚🬄▌🬚🬄▌🬚🬄
🬮🬰🬰🬮🬰🬰🬮🬰🬰🬮🬰🬰🬮🬰🬰🬮🬰🬰🬮🬰🬰🬮🬰🬰
</pre>
</blockquote>
<h2>Generation</h2>
<p>The outline version of Bedstead is generated by an ISO C program.
It emits an XML file that can be processed by
<a href="https://fonttools.readthedocs.io/en/latest/ttx.html">TTX</a>
(part of
<a href="https://fonttools.readthedocs.io/">fontTools</a>)
into an OpenType font.
The bitmap versions (in Bitmap Distribution Format) are then
generated from that OpenType font.</p>
<h2>Copyright</h2>
<p>The program that generates Bedstead and all of the
newly-designed glyphs have been released into the public domain.</p>
<p>I believe that the original SAA5050 bitmap font is essentially
in the public domain in the United Kingdom as a result of
<a href="https://www.legislation.gov.uk/id/ukpga/1988/48/section/55"
>Section 55 of the Copyright, Designs and Patents Act 1988</a>
as applied by
<a href="https://www.legislation.gov.uk/id/ukpga/1988/48/schedule/1/paragraph/14/5"
>subparagraph 14(5) of Schedule 1</a>. I’m not a lawyer, though,
so this may well be wrong.
</p>
<h2>Downloads</h2>
<ul>
<li><a href="bedstead-3.252.zip"><code>bedstead-3.252.zip</code></a>
– Full source and binary distribution containing everything
below and more.</li>
<li><a href="NEWS"><code>NEWS</code></a> – Release notes summarizing
what’s changed between releases.</li>
<li><a href="bedstead.c"><code>bedstead.c</code></a> – The C
program that generates the font.</li>
<li>Finished OpenType fonts:
<ul>
<li><a href="bedstead.otf"><code>bedstead.otf</code></a> –
Bedstead</li>
<li><a href="bedstead-extended.otf"><code>bedstead-extended.otf</code></a>
– Bedstead Extended</li>
<li><a href="bedstead-semicondensed.otf"><code>bedstead-semicondensed.otf</code></a>
– Bedstead Semi Condensed</li>
<li><a href="bedstead-condensed.otf"><code>bedstead-condensed.otf</code></a>
– Bedstead Condensed</li>
<li><a href="bedstead-extracondensed.otf"><code>bedstead-extracondensed.otf</code></a>
– Bedstead Extra Condensed</li>
<li><a href="bedstead-ultracondensed.otf"><code>bedstead-ultracondensed.otf</code></a>
– Bedstead Ultra Condensed</li>
<li><a href="bedstead-bold.otf"><code>bedstead-bold.otf</code></a>
– Bedstead Bold</li>
<li><a href="bedstead-boldextended.otf"><code>bedstead-boldextended.otf</code></a>
– Bedstead Bold Extended</li>
<li><a href="bedstead-boldsemicondensed.otf"><code>bedstead-boldsemicondensed.otf</code></a>
– Bedstead Bold Semi Condensed</li>
<li><a href="bedstead-boldcondensed.otf"><code>bedstead-boldcondensed.otf</code></a>
– Bedstead Bold Condensed</li>
<li><a href="bedstead-boldextracondensed.otf"><code>bedstead-boldextracondensed.otf</code></a>
– Bedstead Bold Extra Condensed</li>
<li><a href="bedstead-boldultracondensed.otf"><code>bedstead-boldultracondensed.otf</code></a>
– Bedstead Bold Ultra Condensed</li>
</ul>
</li>
<li><a href="bedstead-10.bdf"><code>bedstead-10.bdf</code></a>,
<a href="bedstead-20.bdf"><code>bedstead-20.bdf</code></a> –
Bitmap versions at 10 and 20 pixels high.</li>
<li><a href="bedstead-bold-20.bdf"><code>bedstead-bold-20.bdf</code></a>
– Bold bitmap version at 20 pixels high.</li>
<li><a href="bedstead-10-df.png"><code>bedstead-10-df.png</code></a>,
<a href="bedstead-20-df.png"><code>bedstead-20-df.png</code></a>
– 10-pixel and 20-pixel tilesets for use with
<a href="https://www.bay12games.com/dwarves/">Dwarf Fortress</a>.</li>
<li><a href="bedstead-complement.pdf"><code>bedstead-complement.pdf</code></a>
– A complete catalogue of glyphs in PDF.</li>
</ul>
<p>The code to generate Bedstead is held in
<a href="https://git-scm.com/">Git</a>.
You can get your own copy by running</p>
<blockquote>
<p><kbd>git clone https://bjh21.me.uk/bedstead/.git</kbd></p>
</blockquote>
<p>You can also
<a href="https://www.chiark.greenend.org.uk/ucgi/~bjharris/git/bedstead.git/">
browse the repository on-line</a>.
</p>
</body>
</html>
|
