x86 Operating Systems - Printing A Message in BIOS

In this video, we will modify our bootloader program to print a simple message in BIOS using the int 0x10 instruction.

#x86 #nasm

[mybdretaemch]

Hello! I'm thoroughly enjoying your videos. I was curious if you're referencing any specific text prior to this message. Your explanations are clear, but having accompanying text would be beneficial for a deeper understanding. Thank you!

[footballCartoon]

@6:35 when you do:

mov ah, 0x0E # if this is 16-bit program then the accumulator register will look like this in binary 1110 xxxx where the higher byte is filled with hexadecimal 0x0E or 14 in decimal.
mov bh, 0 #assigning memory page number 0, so the register in binary will look like this 0000 0000.

[abraham]

Where can I find the codes for BIOS interrupt? For example, 0x10 video interrupt

[maxmuster]

I like to write directly into b800:0000, 80x25 text screen without using a software interrupt. one row 160 bytes.

[andrebaldermann]

You explain this outstandingly well. Easy to follow and digest. Hope you can make good money out of your skills! First time I understand that deeply, remaining questions solved by chatGPT! So many shitty videos are prominent.I dont get that. You explain in Stanford quality! go apply there xD

[stevenchristenson]

For this program its no big deal to set the SP to your origin since it will use memory above your program but note that the memory above here may not be completely free and its very possible you could put enough stuff in the stack to clobber bios routines or other hardware mapped stuff. Again very unlikely in a program that's probably only 512 byes in size but something to think about.

[mrt_]

why do you do
MOV ax, 0
instead of
XOR ax, ax

[maxmuster]

It is a bootable application, but not a loader if it load no OS.

[maxmuster]

The push and pop instruction not needed.