[comp.sys.ibm.pc] EGA, Compaq, and Compatibility

cramer@kontron.UUCP (Clayton Cramer) (12/09/86)

A few weeks back I posted a problem I was having that appeared to be
incompatibility between the Compaq 386 and the IBM AT.  The problem was
getting DOS to work in 25-line mode after running a program in 43-line
mode on the EGA.  Thanks to a helpful hint from someone on the net,
the problem turned out to be not incompatibility of the Compaq 386,
but something a little more straightforward.

We didn't ANSI.SYS installed on the 386 -- and apparently DOS relies on
ANSI.SYS to operate in 25-line mode after you've run the EGA in 43-line
mode.  I still haven't determined why, and I doubt I will try to find out
why, but this may save someone else some serious head-scratching.

The magic question remains: how do you get the cursor to appear in 43-line
mode on the EGA?  I can see programs like CodeView doing it, but the same
BIOS calls that produce a cursor in 25-line mode don't seem to work in 
43-line mode.

Clayton E. Cramer