The software provided with the ATI Graphics Solution attempts to detect what monitor type is in use by counting how many vertical retraces there are in 18 ticks of the system timer. For a CGA-type display, this would normally be a little under 60; for a Hercules-type, just under 50. The ATI software accepts 45-54 for a Herc, 55-64 for a CGA.
I've written a little utility to display the refresh figures: http://www.seasip.info/DOS/rfsh.zip
. I've tested it on a system with real CGA and Hercules cards fitted, and I usually get results like:
Code: Select all
CGA refreshes: 58
Herc refreshes: 47
When I try it on PCem, I get results on an emulated Hercules that are slightly high (values in the range 53-55) and only about half the expected refresh rate on a CGA (values in the range 28-30). Does anyone know why?