BIOS延迟功能出现问题(INT 15h/AH = 86h) [英] Problems with BIOS delay function (INT 15h / AH = 86h)

问题描述

我今年开始在学校学习汇编，我们才刚刚开始学习像素.

I began studying assembly this year in my school, and we just started learning about pixels.

我们的老师给了我们一些代码，并告诉我们弄乱它，他还告诉我们尝试在代码中实施延迟(ah = 86h | int 15h)，但是当我尝试使用它的位置和颜色的一些像素发生了变化，我不明白为什么

Our teacher gave us some code and told us to mess around with it, he also told us to try and implement delay in the code(ah=86h|int 15h), but when i tried to use it the location and colors of some pixels got changed, and i don't understand why

代码:(只是一段代码，延迟之后，还有更多代码会毁掉)

code: (just a piece of the code, there is some more there also get's ruined after the delay)

mov cx,  20

add [y], 2
mov dx, [y]

paint1RowOf10:

mov bh, 0h 
mov bx, cx

add [x], 1
mov cx, [x]

add [y], 4
mov dx, [y]

mov ax, [red]
mov ah,0ch 
int 10h 

    ; here is a delay part, it waits for 1 seconde
    ; from the help of assembly:
    ; INT 15h / AH = 86h - BIOS wait function. 
    ;CX:DX = interval in microseconds (these are notes from my teacher)

mov ah, 86h
mov cx, 1
mov dx, 2
int 15h 

mov cx, bx
loop paint1RowOf10    

这是结果 http://prntscr.com/9a8lpw 您能告诉我为什么会这样吗?因为据我所知，像素应该排成一行，并且不会改变颜色.

This is the result http://prntscr.com/9a8lpw can you tell me why does this happen? because as far as i see, the pixels are supposed to go in one line, and not change colors.

推荐答案

有一个奇怪的事实，关于int 15h ah = 86h 您还需要设置al = 0，除非它出现不稳定的行为

There is a weird fact, about int 15h ah=86h you also need to set al=0, unless it get an erratic behavior

延迟代码:

mov al, 0 mov ah, 86h mov cx, 1 mov dx, 2 int 15h

mov al, 0 mov ah, 86h mov cx, 1 mov dx, 2 int 15h

我通过试错法发现了它，并且意识到当al = 0时 可以.

I discovered it with try-and-error method and I realize when al=0 it works.

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