I tried even to use MS-DOS 6.22 in VMware Workstation 9.0 (1 processor, 1 core, 16 or 64 mb of RAM) and it's still not working (runtime error 200 at 0002:0095).
(even the original ID-Software's doom2.exe from 1994 runs good on windows 98 virtual machine!!!) What computer or what configuration does REACC need, I wonder?
I also tried to use fteqcc with command-line arguments -facc -fcaseinsens -flax
but there are many errors, below (there is mustn't be any errors, the source code is not changed!):

Code:
E:\QuakeC_laboratory\neh_devkit>compile.bat

E:\QuakeC_laboratory\neh_devkit>fteqcc.exe -facc -fcaseinsens -flax
Compiling without case insensativity
outputfile: progs.dat
compiling !DATASYS.QC
compiling !GLOBALS.QC
compiling !OBJDATA.QC
compiling AI.QC
in function movetarget_f (line 13)
AI.QC:15: error: Unknown value "objerror".
AI.QC:18: error: Unknown value "setsize".
AI.QC:20: error: Unknown value "ex_movetarget".
AI.QC:20: warning: type mismatch for = (pointer and __variant)
AI.QC:24: error: Unknown value "x_movetarget".
AI.QC:24: warning: type mismatch for = (pointer and __variant)
AI.QC:27: error: Unknown value "t_movetarget".
AI.QC:27: warning: type mismatch for = (pointer and __variant)
in function ex_movetarget (line 51)
AI.QC:63: error: Unknown value "find".
AI.QC:63: warning: type mismatch for = (pointer and __variant)
AI.QC:63: warning: type mismatch for = (pointer and __variant)
AI.QC:64: error: Unknown value "vectoyaw".
AI.QC:64: warning: type mismatch for = (pointer and __variant)
AI.QC:65: warning: type mismatch for = (pointer and __variant)
in function t_movetarget (line 84)
AI.QC:97: error: not a function
!DATASYS.QC:190:    sound  is defined here
at global scope
AI.QC:124: error: "{" - not a name
AI.QC:145: error: "{" - not a name
AI.QC:163: error: "{" - not a name

************ ERROR ************
Errors have occured

Error in AI.QC on line 163
It seems that it's impossible to compile Nehahra QC-Pascal on my computer from 2007 using its compiler reacc.

Maybe anyone here is able to compile Nehahra QC?