Category : Files from Magazines
Archive   : WDJAN92.ZIP
Filename : 3N01014A

Listing 1

(1) Change CONFIG.SYS to this (assuming \dos is on drive C):
country=002,,c:\dos\country.sys
device=c:\dos\display.sys con=(ega,,2)

(2) Change AUTOEXEC.BAT to this:
nlsfunc
mode con codepage prepare=((863,850) c:\dos\ega.cpi)
chcp 850

(3) Reboot.

(4) Create, assemble and execute this program:
;Program: Given a certain accented character, return the
; plain equivalent via a code page collating table.
;Author: P. Gulutzan, Ocelot Computer Services Inc.
;Note: Requires MS-DOS 3.3 or later.
; This program was originally prepared with MS-DOS 4.0.
; One would probably want to do a few things differently
; with MS-DOS 5.0 or DR-DOS 6.0.

d_cseg segment byte public 'CODE'
assume cs:d_cseg

xx db 6 (0)

start:
;MS-DOS 3.3 function: "Get pointer to collating sequence table"
mov ax,6506h
mov bx,-1 ;codepage of interest = default
mov cx,512 ;length of receiving buffer
mov di,offset d_cseg:xx ;doubleword pointer to buffer
mov si,seg d_cseg
mov es,si
mov dx,-1 ;country of interest = default
int 21h
;A failure here would probably indicate that CONFIG.SYS
;and/or AUTOEXEC.BAT were not set up properly, in which case:
;no display.
jc endit ;(failure)
;At this point xx has:
; Byte The subcode passed in AL for the function call: 06h
; Dword The address of the collating sequence table
les di,es:[di+1] ;Point to the table
;Now es:di points to the collating sequence table, which has:
; Word Number of characters. Will be < 256 if truncated.
; Byte(s) A lookup table for each character
mov bx,134 ;= the code for a + degree-sign
mov dl,es:[bx+di] ;look it up in the collating table
mov ah,2 ;display it
int 21h
endit:
mov ah,4ch ;stop
int 21h
d_cseg ends

end start

(5) Observe that the result is the letter "A" (ASCII code 65).
(6) Restore the original CONFIG.SYS and AUTOEXEC.BAT files.