68 lines
3.2 KiB
Markdown
68 lines
3.2 KiB
Markdown
---
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layout: page
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title: IBM Color Graphics Adapter (CGA)
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permalink: /devices/pcx86/video/ibm/cga/
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redirect_from:
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- /devices/pc/video/ibm/cga/
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---
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IBM Color Graphics Adapter (CGA)
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---
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### IBM CGA Configurations
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The easiest way for a machine to include an CGA *[Video](/docs/pcx86/video/)* component in its XML configuration file
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is to reference one of the project's predefined CGA configuration files, using the *ref* attribute; eg:
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```xml
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<video ref="/devices/pcx86/video/ibm/cga/ibm-cga.xml"/>
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```
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The referenced XML file automatically defines visual elements (eg, dimensions of the display window and other
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visual indicators), display behaviors (eg, touchscreen support, mouse pointer locking), and the character ROM to load.
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Here's what *ibm-cga.xml* currently looks like:
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```xml
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<video id="videoCGA" screenwidth="960" screenheight="480" scale="true" charset="/devices/pcx86/video/ibm/cga/ibm-cga.json" pos="center" padding="8px">
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<menu>
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<title>Color Display</title>
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<control type="container" pos="right">
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<control type="led" label="Caps" binding="caps-lock" padleft="8px"/>
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<control type="led" label="Num" binding="num-lock" padleft="8px"/>
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<control type="led" label="Scroll" binding="scroll-lock" padleft="8px"/>
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</control>
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</menu>
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</video>
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```
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The following IBM CGA configuration files are currently available:
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- [ibm-cga.xml](ibm-cga.xml)
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- [ibm-cga-dual.xml](ibm-cga-dual.xml)
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- [ibm-cga-keygrid.xml](ibm-cga-keygrid.xml)
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- [ibm-cga-lock.xml](ibm-cga-lock.xml)
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### IBM CGA Character ROM
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There is only one known CGA Character ROM ([ibm-cga.json](ibm-cga.json)), and it is identical to the MDA Character ROM,
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because the ROM contains both the 8x14 MDA and 8x8 CGA fonts.
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As documented in [Video.doneLoad()](/modules/pcx86/lib/video.js):
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[T]here are TWO CGA fonts in the ROM: a thin 5x7 "single dot" font located at offset 0x1000, and a thick 7x7
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"double dot" font at offset 0x1800. The latter is the default font, unless overridden by a jumper setting on
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the CGA card, so it is our default CGA font as well (although someday we may provide a virtual jumper setting
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that allows you to select the thinner font).
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For reference, here are the first 0x80 bytes at offset 0x1800 from this ROM, which contain the font data for the first
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16 8x8 characters:
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0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x7E,0x81,0xA5,0x81,0xBD,0x99,0x81,0x7E, // 0x00001800 ........~......~
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0x7E,0xFF,0xDB,0xFF,0xC3,0xE7,0xFF,0x7E,0x6C,0xFE,0xFE,0xFE,0x7C,0x38,0x10,0x00, // 0x00001810 ~......~l...|8..
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0x10,0x38,0x7C,0xFE,0x7C,0x38,0x10,0x00,0x38,0x7C,0x38,0xFE,0xFE,0xD6,0x10,0x38, // 0x00001820 .8|.|8..8|8....8
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0x10,0x10,0x38,0x7C,0xFE,0x7C,0x10,0x38,0x00,0x00,0x18,0x3C,0x3C,0x18,0x00,0x00, // 0x00001830 ..8|.|.8........
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0xFF,0xFF,0xE7,0xC3,0xC3,0xE7,0xFF,0xFF,0x00,0x3C,0x66,0x42,0x42,0x66,0x3C,0x00, // 0x00001840 ..........fBBf..
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0xFF,0xC3,0x99,0xBD,0xBD,0x99,0xC3,0xFF,0x0F,0x07,0x0F,0x7D,0xCC,0xCC,0xCC,0x78, // 0x00001850 ...........}...x
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0x3C,0x66,0x66,0x66,0x3C,0x18,0x7E,0x18,0x3F,0x33,0x3F,0x30,0x30,0x70,0xF0,0xE0, // 0x00001860 .fff..~.?3?00p..
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0x7F,0x63,0x7F,0x63,0x63,0x67,0xE6,0xC0,0x18,0xDB,0x3C,0xE7,0xE7,0x3C,0xDB,0x18, // 0x00001870 .c.ccg..........
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