Intel assembly in Debug to interact directly to hardware

[mhamini]

I need to do the following..
In Intel Assembly running on DEBUG, bypass OS system calls..
I need a system call that recives in register AH either 1 or 2 and ..
if 1, change the color of every position on the screen to randomly chosen patter
if 2, the system call receives, in BX, offset of address of a string supplied by user, in DL, screen attributes, in CX, the row (0-24), in CH, the column (0-79) and the string will be terminated by a character of choice. This function will display on CGA Screen, the string specified at the column and row with the attributes in DL.
Please Help..

 

[Pinczakko]

to bypass system calls you have to build a device driver (assuming you are running on NT kernel, i.e. winNT/2K/XP). If you running on DOS or win98, it's possible to so directly without the aforementioned driver.