OSDev.org

Posted: **Mon May 16, 2011 8:44 pm**

this is my code:

                use16
                jmp start

;print byte in AL=============================================================
print_byte:     pusha
                push ax         ;save AL

                and al,0f0h     ;get high nibble
                mov cl,4
                shr al,cl
                mov bl,48
                cmp al,0ah
                jl print_hi_nib
                mov bl,55

print_hi_nib:   add al,bl
                mov ah,0eh
                xor bh,bh
                int 10h

                pop ax          ;get back AL
                and al,0fh      ;get low nibble
                mov bl,48
                cmp al,0ah
                jl print_lo_nib
                mov bl,55

print_lo_nib:   add al,bl
                mov ah,0eh
                xor bh,bh
                int 10h

                popa
                ret......................................

flat assembler gave me a strange .bin file, my "PUSHA" had become "DB 60".
anybody knows why?

Posted: **Mon May 16, 2011 11:54 pm**

Code: Select all

eddy@eddy-laptop:~> rasm2 -d 60
pushad
eddy@eddy-laptop:~> rasm2 pusha
60

Did I miss anything? Is that DB there a 0xdb or the DB directive in assemblers?
PS: That rasm2 there comes from radare (http://radare.nopcode.org/y/) - which could be very valuable for inspecting binary files (in radare itself you can scroll trough the assembly)

.

Posted: **Tue May 17, 2011 12:02 am**

so much a great tool, tkx for the suggestion

i finally find out why, the code runs ok, but the thing shown in debug.exe is 'db 60'
what a fun, but interesting, debug.exe doesnt recognise .486 instructions.
seems to be

Posted: **Tue May 17, 2011 12:11 am**

The opcode for pusha is 0x60. Have a look at the Intel Manuals, Volume 2B, "PUSHA".

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"PUSHA" becomes "DB 60"???

"PUSHA" becomes "DB 60"???

Re: "PUSHA" becomes "DB 60"???

Re: "PUSHA" becomes "DB 60"???

Re: "PUSHA" becomes "DB 60"???