48 lines
2.1 KiB
Markdown
48 lines
2.1 KiB
Markdown
---
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layout: post
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title: EGA Support
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date: 2014-07-30 11:00:00
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category: Video
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permalink: /blog/2014/07/30/
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---
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PCjs v1.14.0 now includes basic EGA support. It emulates the EGA hardware well enough to pass the IBM EGA BIOS
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diagnostics and run [Windows 1.01](/devices/pcx86/machine/5160/ega/640kb/win101/) in color. Check out our
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[Windows 1.01 "Server Array"](/devices/pcx86/machine/5160/ega/640kb/array/) demo.
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[<img src="/blog/images/win101-array-demo-small.jpg" alt='Windows 1.01 "Server Array" Demo'/>](/blog/images/win101-array-demo.jpg)
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EGA support is added to a **machine.xml** file using two XML elements; eg:
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```xml
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<video id="videoEGA" model="ega" memory="0x20000" screenwidth="640" screenheight="350"/>
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```
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The *model* attribute must be set to "ega" and the *memory* attribute should be set to the amount of memory
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desired on the card; valid memory sizes are:
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- 0x10000 (64Kb)
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- 0x20000 (128Kb)
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- 0x40000 (256Kb)
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As with the MDA and CGA video cards, the *screenwidth* and *screenheight* attributes specify the size of display
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window, which the browser will then scale up or down, unless a specific overall size has been specified on the
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<machine> element.
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The second required XML element is a <rom> element to load the EGA ROM; eg:
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```xml
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<rom id="romEGA" addr="0xc0000" size="0x4000" file="/devices/pcx86/video/ibm-ega.json" notify="videoEGA"/>
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```
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The *notify* attribute must match the *id* of the <video> element, so that the Video component can load
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the initial 8x14 and 8x8 fonts from the ROM. Support for dynamic loading of fonts from plane 2 of the EGA's memory
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will be added later; however, current support works well enough to allow switching from 25-line mode to 43-line mode,
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which essentially switches from the 8x14 font to the 8x8 font.
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The <video> element also supports a *switches* attribute to specify the type of monitor connected to the EGA;
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this attribute corresponds to the actual switch settings on the EGA card; our default *switches* setting is "0110",
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which selects an Enhanced Color Monitor, enabling the EGA's maximum resolution of 640x350.
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*[@jeffpar](http://twitter.com/jeffpar)*
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*July 30, 2014*
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