Introduction:

The CGA Compatibility Tester, as its name implies, is a program that benchmarks and stresses nearly every capability of the IBM Color Graphics Adapter (CGA). This can be used to:

• Verify that your clone CGA card is 100% compatible with the real IBM CGA
• Similarly, verify how badly your non-CGA card (or software emulator) screws up CGA emulation
• Benchmark adapter RAM speed, to compare with other adapters
• Calibrate your CGA RGB monitor for maximum enjoyment
• Satisfy your curiosity about how CGA can be tweaked

Full documentation is included in the .zip file (see below for download) as "cga_comp.txt". Please consult the documentation for more information.

The following tests are included:

Adapter memory speed benchmarks:

• Interleaved opcode/adapter memory read benchmark
• Interleaved opcode/adapter memory write benchmark
• Adapter Memory-only read benchmark
• Adapter Memory-only write benchmark

Color Select and Mode Control Register tests:

• Border/Overscan color
• Medium-res graphics background color
• High-res graphics foreground color
• Palette display (all six medium-res palettes)

Textmode manipulation:

• 40-column test
• Textmode highcolor background (ie. disable blink)
• Textmode cursor manipulation
• CGA "snow" anomoly
• Font display (simulated via 40-col mode)

Monitor Calibration:

• Brightness calibration
• Contrast calibration
• Moire pattern (high-res horiz/vert/50%)
• Display of all 16 colors

MC6845 CRTC programming:

• Horizontal retrace demo
• Vertical retrace detection
• Row reprogramming (80x100)
• Row/Column reprogramming (90x30)
• Interlaced mode test
• Horizontal/Vertical sync position test
• Start Address register test

Downloads:

Download the CGA Compatibility Tester, version 0.5a

Reference Video

To provide a reference to how the tester works with a real 100% IBM CGA card and monitor, a Full-D1 MPEG-2 video of some of the more demanding tests is available courtesy of The Internet Archive. It is highly recommended to watch the video before attempting to use the tester, so that you can have an idea of what some of the more demanding displays are supposed to look like.

Here is a streaming version of that video, for the curious:

Additional References:

• http://www.vintage-computer.com/vcforum/showthread.php?t=13722 is the discussion where the need for this program was discovered. You can find some CGA clone test results there as well.
• CGACAL is a program that displays a simple color chart, and the webpage has an image of what that chart is supposed to look like. There is also an explanation of why color index #6 is generated as dark yellow but shows up on the monitor as brown, something that has caused a lot of confusion for emulator authors.