45 lines
1.4 KiB
Markdown
45 lines
1.4 KiB
Markdown
# Intro
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Mobitec flip-disc displays use MC27C1001 EPROM-s to store the
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firmware (?) and fonts.
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In the `firmware/` directory you can find two ROM dumps.
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# Useful commands
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To extract font sections:
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```
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dd if=mobitec-1682-r7-bib-01979-r3.bin of=mobitec-1682-r7-bib-01979-r3-fonts.bin skip=64 bs=1024
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dd if=mobitec-01682-r7-bib-01369-r9.bin of=mobitec-01682-r7-bib-01369-r9-fonts.bin skip=64 bs=1024
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```
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For diffing font sections:
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```
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dhex mobitec-1682-r7-bib-01979-r3-fonts.bin mobitec-01682-r7-bib-01369-r9-fonts.bin
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```
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# Dump structure
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The firmware seems to be located in the first 7KiB and the font data
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starts at 0x10000 offset.
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The font beginning marker seem to consist of a character from `a` to `z`
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followed by at least 60 null characters.
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They don't seem aligned or indexed in any way so easiest is just to scan
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for known markers.
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After the beginning marker you can find the lookup table which maps
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printable ASCII characters to a glyph address.
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The lookup table is 190 bytes (95x 16-bit addresses) which correspond
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to ASCII characters 32 up to 126.
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Not all fonts include all characters, missing glyphs are represented by address 0.
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Note that the glyph address is relative to the beginning of font structure,
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beginning marker inclusive.
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At the glyph address first width and height of the glyph are found represented
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by two 8-bit integers. The actual bitmap data follows in 8x8 pixel tiles
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packed together as 8 bytes.
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