All of the forementioned functions are unique in what they accomplish, but at first the abundance does seem somewhat exagerated. Int 21h AH=02h Write Character To Standard Output This function interprets the character codes 7 (Beep), 8 (Backspace), 9 (Tab), 10 (Linefeed), and 13 (Carriage return). All other character codes are displayed. Backspace is nondestructive … Read more
I don’t know of anyway to step through the execution of a .bat file but you can use echo and pause to help with debugging. ECHO Will echo a message in the batch file. Such as ECHO Hello World will print Hello World on the screen when executed. However, without @ECHO OFF at the beginning … Read more
copy NUL EmptyFile.txt DOS has a few special files (devices, actually) that exist in every directory, NUL being the equivalent of UNIX’s /dev/null: it’s a magic file that’s always empty and throws away anything you write to it. Here’s a list of some others; CON is occasionally useful as well. To avoid having any output … Read more
Looking at how you defined your input buffer (buf: db 20 dup (‘$’)), I get it that you want to cut corners and have the input already $-terminated ready for re-displaying it. Sadly this messes up the required settings for the DOS input function 0Ah and your program is in serious problems with a potential … Read more
It’s true that DOS doesn’t offer us a function to output a number directly. You’ll have to first convert the number yourself and then have DOS display it using one of the text output functions. Displaying the unsigned 16-bit number held in AX When tackling the problem of converting a number, it helps to see … Read more