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Motorola 6847: Difference between revisions

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The MC6847 is a video display generator chip that is designed for the 6800 family of microprocessors.  It reads data from memory (via the [[SAM]] chip) and displays the contents on screen.  The 6847 is used on Coco 1 and 2's only; this function was replaced by the custom [[GIME]] chip in Coco 3 models.
The MC6847 is a video display generator chip that is designed for the 6800 family of microprocessors.  It reads data from memory (via the [[SAM]] chip) and displays the contents on screen.  The 6847 is used on Coco 1 and 2's only; this function was replaced by the custom [[GIME]] chip in Coco 3 models.


The chip provides a 32x16 alphanumeric display, or graphic displays up to 256x192 pixels in resolution.  Additionally, a variety of "semigraphics" modes are provided.
The chip provides a 32×16 alphanumeric display, or graphic displays up to 256×192 pixels in resolution.  Additionally, a variety of "semigraphics" modes are provided.


On the Coco, the familiar dark-green on light-green text is generated as a fundamental function of this chip.
On the Coco, the familiar dark-green on light-green text is generated as a fundamental function of this chip.


In Coco 1's and most Coco 2's, the 6847 is not capable of displaying lowercase.  Instead, lower case text appears inverted.   Later Coco 2's replaced the 6847 with a 6847T1 that can display proper lower case text.
In Coco 1's and most Coco 2's, the 6847 is not capable of displaying lowercase.  Instead, lower case text appears inverted. Later Coco 2's replaced the 6847 with a 6847T1 that can display proper lower case text.


==See Also==
==See Also==
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*Wikipedia article on the [http://en.wikipedia.org/wiki/Motorola_6847 Motorola 6847]
*Wikipedia article on the [http://en.wikipedia.org/wiki/Motorola_6847 Motorola 6847]
*Datasheet http://instruct1.cit.cornell.edu/courses/ee476/ideas/mc6847.pdf
*Datasheet http://instruct1.cit.cornell.edu/courses/ee476/ideas/mc6847.pdf
[[Category:Hardware]]

Revision as of 21:53, 10 September 2015

The MC6847 is a video display generator chip that is designed for the 6800 family of microprocessors. It reads data from memory (via the SAM chip) and displays the contents on screen. The 6847 is used on Coco 1 and 2's only; this function was replaced by the custom GIME chip in Coco 3 models.

The chip provides a 32×16 alphanumeric display, or graphic displays up to 256×192 pixels in resolution. Additionally, a variety of "semigraphics" modes are provided.

On the Coco, the familiar dark-green on light-green text is generated as a fundamental function of this chip.

In Coco 1's and most Coco 2's, the 6847 is not capable of displaying lowercase. Instead, lower case text appears inverted. Later Coco 2's replaced the 6847 with a 6847T1 that can display proper lower case text.

See Also