需要關於彙編器視頻模式的幫助

Question

我正在爲我的課程做一些編碼，我認爲我在正確的軌道上，但是我遇到了垂直線問題。當我運行這段代碼時，它會在同一個確切的位置同時繪製兩條水平線，但是我需要沿着垂直線50,50至50,75而不是水平線50,50至75,50從第2條線移動。我不問的答案我只是需要一個微調和解釋，謝謝：

; video.asm 
; uses interrupts to set video mode and draw a line 

include 'emu8086.inc' 

org 100h ; set location counter to 100h 

jmp CodeStart 

DataStart: 
    xStart1 dw 50  ; x coordinate of line start 1 
    yStart1 dw 50  ; y coordinate of line start 1 
    xStart2 dw 50  ; x coordinate of line start 2 
    yStart2 dw 50  ; y coordinate of line start 2 
    length dw 25  ; length of line 

CodeStart: 

    ; set the video mode 320x200, 256 colors 
    mov al, 13h 
    mov ah, 0 
    int 10h 

    ; initialize cx (x coord) to xStart1 + length 
    ; initialize bx (y coord) to yStart2 + length 
    mov cx, xStart1 
    mov bx, yStart2 
    add cx, length 
    add bx, length 


    ; loop from (xStart1+length) to xStart1 to draw a horizontal line 
    ; loop from (yStart1+length) to yStart1 to draw a vertical line 
    LoopStart:  

     ; draw a pixel 
     ; set color in al, x in cx, y in dx 
     mov al, 50 
     mov dx, yStart1 

     ; set sub function value in ah to draw a pixel 
     ; and invoke the interrupt 
     mov ah, 0ch 
     int 10h 

     ; decrement the x coord for line 1 
     ; decrement the y coord for line 2 
     sub cx, 1 
     sub bx, 1 

     ; test to see if x coord has reached start value 
     cmp cx, xStart1 

    ; continue loop if cx >= xStart1 
    jae LoopStart 

    ret 

Answer 1

而是保持不變y和不同x的，保持不變x並改變y