ASM-EXP4

04.asm

;https://www.kmahyyg.xyz/2018/ASM-exp-report2/  For more details.

         mov ax,0xb800                 ;screen buffer
         mov es,ax

         ; show string "201x1xx0xxx Yxxx xx xxxxx"
         ; 0x07 == bell (in ascii), saved in parital addr
         ; 0x07 saved in odd addr, flash, char options
         mov byte [es:0x00],'2'
         mov byte [es:0x01],0x05
         mov byte [es:0x02],'0'
         mov byte [es:0x03],0x05
         mov byte [es:0x04],'1'
         mov byte [es:0x05],0x05
         mov byte [es:0x06],'x'
         mov byte [es:0x07],0x05
         mov byte [es:0x08],'1'
         mov byte [es:0x09],0x05
         mov byte [es:0x0a],'x'
         mov byte [es:0x0b],0x05
         mov byte [es:0x0c],'x'
         mov byte [es:0x0d],0x05
         mov byte [es:0x0e],'0'
         mov byte [es:0x0f],0x05
         mov byte [es:0x10],'x'
         mov byte [es:0x11],0x05
         mov byte [es:0x12],'x'
         mov byte [es:0x13],0x05
         mov byte [es:0x14],'x'
         mov byte [es:0x15],0x05
         mov byte [es:0x16],' '
         mov byte [es:0x17],0x05
         mov byte [es:0x18],'Y'
         mov byte [es:0x19],0x05
         mov byte [es:0x1a],'x'
         mov byte [es:0x1b],0x05
         mov byte [es:0x1c],'x'
         mov byte [es:0x1d],0x05
         mov byte [es:0x1e],'x'
         mov byte [es:0x1f],0x05
         mov byte [es:0x20],' '
         mov byte [es:0x21],0x05
         mov byte [es:0x22],'x'
         mov byte [es:0x23],0x05
         mov byte [es:0x24],'x'
         mov byte [es:0x25],0x05
         mov byte [es:0x26],' '
         mov byte [es:0x27],0x05
         mov byte [es:0x28],'x'
         mov byte [es:0x29],0x05
         mov byte [es:0x2A],'x'
         mov byte [es:0x2B],0x05
         mov byte [es:0x2C],'x'
         mov byte [es:0x2D],0x05
         mov byte [es:0x2E],'x'
         mov byte [es:0x2F],0x05
         mov byte [es:0x30],'x'
         mov byte [es:0x31],0x05

         mov ax,number                 ;get the base addr of number seg
         mov bx,10

         ;get the base addr of datasg
         mov cx,cs
         mov ds,cx

         ;calc the 10^0
         mov dx,0
         div bx
         ; alfter bios exit with code 0, computer will jump to 0x7c00
         mov [0x7c00+number+0x00],dl   ;save the 10^0
         
         ;calc the 10^1
         xor dx,dx
         div bx
         mov [0x7c00+number+0x01],dl 

         xor dx,dx
         div bx
         mov [0x7c00+number+0x02],dl

         xor dx,dx
         div bx
         mov [0x7c00+number+0x03],dl

         xor dx,dx
         div bx
         mov [0x7c00+number+0x04],dl
         
         mov cx,0xb850
         mov es,cx 
         ;show the offset addr in dec
         mov al,[0x7c00+number+0x04]
         add al,0x30
         mov [es:0x1a],al
         mov byte [es:0x1b],0x04
         
         mov al,[0x7c00+number+0x03]
         add al,0x30
         mov [es:0x1c],al
         mov byte [es:0x1d],0x04
         
         mov al,[0x7c00+number+0x02]
         add al,0x30
         mov [es:0x1e],al
         mov byte [es:0x1f],0x04

         mov al,[0x7c00+number+0x01]
         add al,0x30
         mov [es:0x20],al
         mov byte [es:0x21],0x04

         mov al,[0x7c00+number+0x00]
         add al,0x30
         mov [es:0x22],al
         mov byte [es:0x23],0x04
         
         mov byte [es:0x24],'D'
         mov byte [es:0x25],0x07
          
         infi: jmp near infi               ; infinity loop here
      
  number db 0,0,0,0,0     ; numbers saved in order to be shown next
  
  times 54 db 0           ; padding the remainder with 0
                          ; times <remainder> db 0	
                          
         db 0x55,0xaa       ; set bootable flag