[Coco] Disto SC add-ons

[Roger Taylor]

At 07:19 PM 1/2/2009, you wrote:

>I don't happen to have a set of specs on that particular crt 
>controller Roger,
>but I would suspect a simple doubling of the dot clock crystal would make it
>compatible with vga, which needs a minimum h rate of 31.5Khz.  That would
>make it a 29 Mhz crystal I believe.  That might however, need a 2x faster
>character data rom too.  My WP-RS was running on the usual 14.x Mhz crystal,
>but with reworked blanking and sync times so it ran at about 18Khz h rate,
>and 70 Hz v rate.  A Maggy 12" PC Monitor 80 was happy as a clam running at
>that speed for over a decade once the h oscillator coil slug was backed out
>for the higher sweep rate.  That all served to make the display much bigger
>and more easily read, which was the main idea.

I first looked all over the web and couldn't find any pinouts of the 
CRT9128.  It looks like Tony's article covers all that, but it's a 
scanner capture of the magazine pages and I'm not sure if there's any 
text copy there for engines to see.  I wonder if that particular 
add-on was a dud compared to his other popular boards?

Anyway, I'm looking forward to making some personal experimental 
add-ons one day using the MEB connector.

-- 
Roger Taylor

http://www.wordofthedayonline.com