The 'Video RAM' test in versions 2.1 and 3.0 of CheckIt software will report errors if less than 256 KB of video RAM is fitted to an IBM EGA card.
This problem may also apply to non-IBM EGA cards - I have not checked.
I have an IBM EGA card with the default of 64 KB of video RAM fitted (i.e. the optional Graphics Memory Expansion Card is not fitted).
I then run CheckIt version 2.1
I navigate to the SysInfo/Configuration screen.
As expected, that screen indicates that there is 64 KB of video RAM. (photo)
I then navigate to the video tests, then execute the 'Video RAM' test.
After a few seconds, I see the following:
If I use version 3.0 instead of version 2.1 of CheckIt, I see the same result, excepting that the bits showing as having failed are somewhat random.
Note that the errors start at address 0A0000h.
If I then upgrade the video RAM to 128 KB, the errors start at address 0A8000h.
If I then upgrade the video RAM to 192 KB, the errors start at address 0AC000h.
If I then upgrade the video RAM to 256 KB, the video RAM test passes.