[Coco] Simple 8-bit VGA Graphics Card

[Juan Castro]

Other options:

- The F18A: http://codehackcreate.com/archives/30 - Texas TMS9918 compatible
- Veronica's VGA controller (though that's a work in progress):
http://quinndunki.com/blondihacks/

On Mon, Jan 28, 2013 at 12:09 AM, Kip Koon <computerdoc at sc.rr.com> wrote:
> Hello My Fellow Cocoers,
>
> In the course of the development of my 6809 computer, several people have
> suggested that I add a video controller.  Well, I found one that looks very
> interesting and quite simple, only the guy speaks German, so if anyone knows
> German, I’d like to ask that person to translate the documentation in the
> zip files.  The link below is via Goggle translator, so I can read the web
> page with ease.
>
> http://translate.google.com/translate?sl=de
> <http://translate.google.com/translate?sl=de&tl=en&js=n&prev=_t&hl=en&ie=UTF
> -8&layout=2&eotf=1&u=http%3A%2F%2Fwww.ulrichradig.de%2Fhome%2Findex.php%2Fcp
> ld%2F8bit_c_graka>
> &tl=en&js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Fwww.ulrich
> radig.de%2Fhome%2Findex.php%2Fcpld%2F8bit_c_graka
>
> The following info is from a file in the zip file in German.
>
>
>
> DatenBus Steckerbelegung
>
>
>
> Pin          Funktion
>
> 1              Daten1
>
> 2              Daten0
>
> 3              Daten3
>
> 4              Daten2
>
> 5              Daten5
>
> 6              Daten4
>
> 7              Daten7
>
> 8              Daten6
>
> 9              A1
>
> 10           A0
>
> 11           N.C.
>
> 12           WR
>
> 13           GND
>
> 14           VCC (+5V)
>
>
>
> It looks quite straight forward.  So far I figure that the input lines to
> the video card are 8 data bits, 2 address bits, a write bit, ground and +5
> volts.  Really a very simple interface.
>
>
>
> Another file has the following.
>
>
>
> 8 Bit Grafikkarte für µC
>
>
>
> Garfikkarte hat eine Auflösung von 256x256Pixel mit 32Farben (6Bit)
>
> Unterstützt 60Hz mit 32MHz Quarz und 75Hz mit 40Mhz Quarz im Auflösungsmodus
> 640x480
>
>
>
> Adressen:
>
>
>
> Register 0 = Pixel in horizontaler Richtung (8Bit) Spalte
>
> Register 1 = Pixel in Verticaler Richtung (8Bit) Zeile
>
> Register 2 = Farbe (6Bit)
>
> Register 3 = not use
>
>
>
> Looks like it’s 256 bits x 256 bits x 32 colors using a 6 bit digital to
> analog converter.
>
> A horizontal frequency of 60Hz with a 32MHZ crystal and 75Hz with a 40MHz
> crystal.  The result is a 640 by 480 VGA screen.
>
> Register 0 is the horizontal pixel to be accessed.
>
> Register 1 is the vertical pixel to be accessed.
>
> Register 2 is the color to be written to the above addressed memory
> location.
>
>
>
> The really nice thing about this interface is the custom video controller
> chip which has its own 64KBs of memory.  No need (yet) for my computer to
> have a copy of the video info stored in the computer’s main memory, however
> if I am to merge the graphics commands back into Grant’s 6809 Extended
> Basic, I’ve got my work cut out for me.  J  More fun, Yes!  I’m really
> thinking seriously of implementing this simple VGA video controller.
>
> I’ll leave the rest for you guys to read on the web site and in the
> downloadable zip file.  I’m sure I’ll come across other video controllers
> and I’m sure you guys have ideas too for a video controller of your own for
> a 6809 8-bit microprocessor based computer system.  Have Cocoing & 6809ing!
>
> Kip
>
>
>
>
> --
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