使用的系统是manjaro linux。使用的工具是emu8086模拟器，是安装在windows xp 系统里面的（用wine也能运行），真实的运行环境是windows xp 虚拟机，语法格式为masm。因为本人已经很久没用windows,而汇编的开发工具windows是比linux好的，特别是这个emu8086模拟器，非常的好用。但是目前来看emu8086是最好用的开发环境了，不光具有调试功能，而且集成了内存视图，文件列表（lst文件）等非常使用的工具，emu8086使用的是masm语法。其实本人更喜欢nasm的语法格式。
开始正题：
用汇编在显示器上实现hello world其实也不难。下面给出代码并解释。下面给出masm格式的代码实现，在后面会给出一份nasm格式的实现。其实都差不多。
; You may customize this and other start-up templates;
; The location of this template is c:\emu8086\inc\0_com_template.txt
mov ax,0xb800
mov ds,ax ;跳转到显存的位置
mov [0x00],0x41 ;字符a
mov [0x01],0x04 ;颜色为红色
mov [0x02],'s'
mov [0x03],0x14 ;随便取色
mov [0x04],'s'
mov [0x05],0x24
mov [0x06],'e'
mov [0x07],0x34
mov [0x08],'m'
mov [0x09],0x44
mov [0x0a],'b'
mov [0x0b],0x54
mov [0x0c],'l'
mov [0x0d],0x64
mov [0x0e],'y'
mov [0x1f],0x74
mov [0x10],'.'
mov [0x11],0x84
db 510-(0x5f) dup(0)
db 0x55,0xaa
首先显示文本是需要用到显卡的显存的，其实就是一块存储器，一般有几M。对应内存地址的一段地址空间。这个地址空间的起点是0xb800。这个是固定的。别的设备也会站一段属于自己的地址空间。mov ax,0xb800 mov ds,ax就是跳转到显存的起始位置。
字符的结构由两个byte组成。第一个byte表示ascii表对应的编号比如a对应的编号是0x41,也可以直接写成'a'.
第二个byte表示颜色，颜色的格式是krgb irgb。前4位表示背景色，后4位表示前景色。k表示是否闪烁，1表示闪烁，0表示不闪烁。i表示是否是灰度，1表示是，0表示否。
例如0x04,0对应0000，也就是krgb全是0，表示背景色纯黑不闪烁。4对应0100，表示无灰度的红也就是irgb中的r为1，其它都为0。
最后要说一些最后两行。
先说说最后一行 db 0x55,0xaa。db表示手动写入内容。这里手动写入0x55和0xaa。这两个两个值是什么意思？这段程序是要写到主引导扇区的，主引导扇区规定最后两个字节就是这两个，最为结束的标记。主引导扇区有512个字节。而且主引导扇区需要填满。所以512-2还有510个字节。需要减去我们写的代码占用的大小。我们怎么知道我们写的代码在内存中的大小呢？可以通过lst文件查看。这个lst数据是可以通过工具生成的。emu8086自带这个功能直接帮你生成。位置在调试器的view->listing
EMU8086 GENERATED LISTING. MACHINE CODE <- SOURCE.
noname.bin_ -- emu8086 assembler version: 4.08
[ 2021-3-25 -- 18:31:09 ]
===================================================================================================
[LINE] LOC: MACHINE CODE SOURCE
===================================================================================================
[ 1] :
[ 2] : ; You may customize this and other start-up templates;
[ 3] : ; The location of this template is c:\emu8086\inc\0_com_template.txt
[ 4] :
[ 5] 0000: B8 00 B8 mov ax,0xb800
[ 6] 0003: 8E D8 mov ds,ax
[ 7] :
[ 8] 0005: C6 06 00 00 41 mov [0x00],0x41 ;字符A
[ 9] 000A: C6 06 01 00 04 mov [0x01],0x04 ;颜色为红色
[ 10] :
[ 11] 000F: C6 06 02 00 73 mov [0x02],'s'
[ 12] 0014: C6 06 03 00 14 mov [0x03],0x14
[ 13] :
[ 14] 0019: C6 06 04 00 73 mov [0x04],'s'
[ 15] 001E: C6 06 05 00 24 mov [0x05],0x24
[ 16] :
[ 17] 0023: C6 06 06 00 65 mov [0x06],'e'
[ 18] 0028: C6 06 07 00 34 mov [0x07],0x34
[ 19] :
[ 20] 002D: C6 06 08 00 6D mov [0x08],'m'
[ 21] 0032: C6 06 09 00 44 mov [0x09],0x44
[ 22] :
[ 23] 0037: C6 06 0A 00 62 mov [0x0a],'b'
[ 24] 003C: C6 06 0B 00 54 mov [0x0b],0x54
[ 25] :
[ 26] 0041: C6 06 0C 00 6C mov [0x0c],'l'
[ 27] 0046: C6 06 0D 00 64 mov [0x0d],0x64
[ 28] :
[ 29] 004B: C6 06 0E 00 79 mov [0x0e],'y'
[ 30] 0050: C6 06 1F 00 74 mov [0x1f],0x74
[ 31] :
[ 32] 0055: C6 06 10 00 2E mov [0x10],'.'
[ 33] 005A: C6 06 11 00 84 mov [0x11],0x84
[ 34] :
[ 35] : ;times 510-($-$$) db 0
[ 36] 005F: 00 00 00 00 00 00 00 00 00 00 00 00 db 510-(0x5f) dup(0)
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00
[ 37] 01FE: 55 AA db 0x55,0xaa
[ 38] :
[ 39] :
[ 40] :
[ 41] :
[ 42] :
[ 43] :
[ 44] :
[ 45] :
[ 46] :
===================================================================================================
===================================================================================================
注意标号为36的地方，地址值为5f,也就是表示我们前面显示文字的代码占用了5f个字节的地址空间，所以db 510-(0x5f) dup(0)这行代码就非常好解释了。dup表示重复执行次数为510-（0x5f）,十进制和二进制是可以混合写的。dup(0) 表示写入的内容为0，就是将剩余的空间全部填充为0.
下面给出nasm格式的代码，其实差不多只是语法不太一样。nasm可以指定值的单位是byte还是word 1word=2byte.重复使用times而不是dup。
mov ax,0xb800
mov ds,ax
mov byte [0x00],0x41 ;字符A
mov byte [0x01],0x04 ;颜色为红色
mov byte [0x02],'s'
mov byte [0x03],0x14
mov byte [0x04],'s'
mov byte [0x05],0x24
mov byte [0x06],'e'
mov byte [0x07],0x34
mov byte [0x08],'m'
mov byte [0x09],0x44
mov byte [0x0a],'b'
mov byte [0x0b],0x54
mov byte [0x0c],'l'
mov byte [0x0d],0x64
mov byte [0x0e],'y'
mov byte [0x1f],0x74
mov byte [0x10],'.'
mov byte [0x11],0x84
times 510-($-$$) db 0
;db 510-(0x5f) dup(0)
db 0x55,0xaa
每次都要计算非常的麻烦，更简单的方法就是设置标志位,在开始的地方设置start标志位，名字可以随便取。结束的地方设置另一个标志位两个相减。
start:
mov ax,0xb800
mov ds,ax
mov [0x00],0x41 ;字符A
mov [0x01],0x04 ;颜色为红色
...
current:
db (current-start) dup(0)
还有跟简单的方法就是使用提供的特殊符号来表示
db ($-$$) dup(0) $表示开始，$$表示结束。
最后的显示效果，是有不同颜色的哟！虽然颜色很丑。。。