Sitenotice: 11/29/2018: The wiki is back. It turns out, some anti-virus product on my web server had an issue with the latest version of PHP. My server techs have resolved this issue, and things should be working again. During the investigation, I did restore to a backup from September. There is a chance that any changes done since then were lost, but I do not recall any edits. --OS-9 Al
8/30/2016: Massive re-work is being done on the InfoBox Templates. Read that page to keep up with the plan for that, and adding better keyword tags (categories) to all the pages. --OS-9 Al (talk) 15:28, 31 August 2016 (CDT)
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.
- Wikipedia article on the Motorola 6847
- Datasheet http://instruct1.cit.cornell.edu/courses/ee476/ideas/mc6847.pdf