INT 2Fh - DR-DOS NLSFUNC 4.01+ - ENHANCED INSTALLATION CHECK AX = 1400h BX = 0EDCh Return: AL = status 00h not installed, OK to install 01h not installed, not OK to install (for example under a multitasker) FFh installed ES:DI -> version signature ("4.01$".."4.04$" for 4.01..4.04) flags may be destroyed Program: NLSFUNC 4.01+ is currently an independent project under development by Matthias Paul. It is not yet publically available, but as NLSFUNC 4.00 did, it will probably become available with future DR-DOS releases. Notes: If BX <> 0EDCh on entry, DR-DOS NLSFUNC 4.01+ performs the standard installation check (INT 2F/AX=1400h), and does not change ES:DI. DR DOS 5.0+ NLSFUNC 3.00+ returns CF set and AX=0001h, if AL was not 00h, FEh, or FFh on entry. NLSFUNC 4.01+ will use the ES:DI enhancement to check the driver version and calculate displacements into the resident driver for runtime updates of internal structures like the local NLS database filespec, etc. If the returned ES points into the HMAsee High Memory Area (ES=FFFEh) care should be taken to actually access the HMAsee High Memory Area while checking the version signature and updating resident data (mutex with local A20(Address line 20) The 80286 and higher CPUs allow addresses in real mode to extend slightly beyond the one megabyte mark, which causes an incompatibility with some older programs which expect such addresses to wrap back to the beginning of the address space. For complete compatibility with the 8088, newer machines thus contain circuitry which permits the twenty-first address line (A20) to be disabled. The CPU then effectively has only twenty address lines in real mode, just as the 8088 does, and addresses which would extend beyond the one megabyte mark wrap to the beginning of the address space. See also High Memory Area, Real Mode. enable/disable). While previous issues of NLSFUNC installed under a multitasker, DR-DOS NLSFUNC 4.01+ will actually adapt to work properly in this environment. SeeAlso: AX=1400h"NLSFUNC.COM",AX=14FEh,AX=14FFh,INT 21/AH=65h