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The EGA has a nice underline feature. If you send the video card a certain code, you can have certain characters underlined. Listing 1 below is the code to set the EGA card. Listing 2 (at right) is some demo code to show you what is being done. Typing UNDER1 at the DOS prompt will "turn it on". Typing UNDER1 N at the DOS prompt will "turn it off". First enter UNDER1 at the DOS prompt. Then enter UNDER2 to see the text. Now enter UNDER1 N and UNDER1 each in turn to see the underline appear and disappear. ;; Listing 1 .model tiny .code mov al,[5Dh] ; the 'N' in the FCB xor bx,bx ; could use [82h] mov ds,bx mov ah,[0485h] cmp al,4Eh jz NotN dec ah NotN: mov dx,[0463h] mov al,14h out dx,ax ret .end |
;; Listing 2 .model tiny .code mov ax,0600h mov bh,02h xor cx,cx mov dx,1950h int 10h mov ah,02 xor bh,bh xor dx,dx int 10h mov ax,0950h mov bx,0001 mov cx,0028h int 10h mov ah,02 mov dx,0028h int 10h mov ax,0943h mov bl,02h int 10h ret .endPlease note that this will only work on an EGA or better card. ¥ |
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