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IanSB / RGBtoHDMI

Bare-metal Raspberry Pi project that provides pixel-perfect sampling of BBC Micro video and conversion to HDMI
GNU General Public License v3.0
128 stars 6 forks source link

External Amiga Connection possible? #11

Open thbreidenbach opened 2 years ago

thbreidenbach commented 2 years ago

The internal Amiga CPLD Boards are great but I do a lot of board repairs where initial testing is easier with an external Adapter like the D520 (which is unobtainium as of now) I wonder how the chances are to use the external 12bit Board on the Video Port of an Amiga? Even on AGA Machines I had great success with the internal Adapter even though there's missing colors in higher color depth. For testing or Workbench this is a non issue.

IanSB commented 2 years ago

The external adapter should work with the Amiga's digital output on the Video Port but as it's only RGBI there will be limited colours. No need for the 12 bit extender as the bits would connect to the standard 8 bit header much like a CGA PC.

thbreidenbach commented 2 years ago

Hi, thanks for your answer. Isn’t digital out (rgbd) more like the digital representation of composite (b/w) output?

Am 02.04.2022 um 23:27 schrieb IanSB @.***>:

The external adapter should work with the Amiga's digital output on the Video Port but as it's only RGBI there will be limited colours. No need for the 12 bit extender as the bits would connect to the standard 8 bit header much like a CGA PC.

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IanSB commented 2 years ago

Isn’t digital out (rgbd) more like the digital representation of composite (b/w) output

I don't know, I've not tried it but the bits are labelled Digital R, G, B and Intensity which is the same as IBM CGA which gives 16 possible colours. The mapping of which digital bits are set depending on the input 12 bit RGB is done in the hybrid and I'm guessing it is mapping the input colour to the nearest RGBI colour for a limited palette.