real-mode – Make Me Engineer

Printing out a number in assembly language?

May 27, 2023 by Tarik

Have you tried int 21h service 2? DL is the character to print. mov dl,’A’ ; print ‘A’ mov ah,2 int 21h To print the integer value, you’ll have to write a loop to decompose the integer to individual characters. If you’re okay with printing the value in hex, this is pretty trivial. If you … Read more

What are the segment and offset in real mode memory addressing?

November 22, 2022 by Tarik

When Intel was building the 8086, there was a valid case for having more than 64KB in a machine, but there was no way it’d ever use a 32-bit address space. Back then, even a megabyte was a whole lot of memory. (Remember the infamous quote “640K ought to be enough for anybody”? It’s essentially … Read more