CGA Compatibility Test Suite - RGBI Capture
0I captured these tests with a Datapath at 720x480 and upscaled 3x via nearest neighbor to 1920x1440p. The video is supposed to be silent.
I did not show any composite video tests, I may show them later. I also did not show the linearity and convergence test because that one produces color without sync and my capture card does not like that.
If you want true 100% compatibility with all software which supports CGA, you really need an IBM PC Model 5150 or IBM PC/XT Model 5160 or IBM PC Portable Model 5155 running at with an 8088 CPU running at 4.77MHz. This is being run on my IBM PC/XT.
The early, pre-TL/SL Tandy 1000s can, if setup properly, show everything correctly which does not rely the text glyphs themselves. CGA clones may not show everything correctly unless they are full off-the-shelf-logic clones of the IBM design. EGA and VGA cards will typically fail in spectacular ways with this program.
Specific comments :
Border/Overscan color - The border color can only be freely changed in text modes. In graphics modes it shares the background color. This border change is shown in the 80-column text mode. The active display is 640x200 pixels, but is always squished on original displays. Most emulators will not show borders or only show thin ones, but real CGA borders are thick.
Medium-res background - Same as above, only using the 40-column text mode.
High-res foreground - Uses 640x200 graphics mode, the background is always black.
Medium-res Palettes - "Low" and "High" are the difference of whether the Intensity signal is active or not., the cyan/red/white palettes are the only palettes available in true CGA Mode 05h.
Tex mode highcolor - If blinking is enabled for a text cell, you can only set its background color to the first eight colors.
Cursor control - A Tandy 1000 needs to be set to 200-line mode for the cursor to display correctly.
CGA Snow - Only seen in 80-column text due to bandwidth limitations of the original CGA card emulators usually do not bother or do not show this screen correctly.
Horizontal retrace - Trixter's showing off his demoscene roots with these raster bars!
Row Reprogramming - The second image is using more varied text characters for detail, so your device may not display the image perfectly if the text characters vary markedly from the IBM CGA card.
Row/Column Reprogramming - This an extreme use of the card to go beyond the typical 80x25 text mode. A real CRT will likely cut off some portion of the text. I had to recenter the image in the Datapath to show it all, but my device captured all but one line of the display correctly.
Display Repositioning - Rarely implemented in emulators, this can be seen when Manannan kills Gwydion in King's Quest III with CGA and Tandy Graphics and with games like Jungle Hunt which allow you to position the horizontal starting point of the screen. Occasionally the screen will go black for a frame or two due to the capture card needing to recall the mode being displayed.
Start address reprogramming - This test was always strange when it gets to the horizontal portion because it works nothing like the vertical portion.
Motion test plate - This will likely never be perfectly smooth from a capture card, CGA displays at 59.92Hz and capture cards expect 59.94Hz or 60Hz.
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