From 94a6d7da27dc9c162e97d577d4a17d1aa237b393 Mon Sep 17 00:00:00 2001 From: Carlos Fenollosa Date: Mon, 29 Sep 2014 11:54:35 +0200 Subject: [PATCH] tty mode explained --- 02-bootsector-print/README.md | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/02-bootsector-print/README.md b/02-bootsector-print/README.md index 766547b..9b5d538 100644 --- a/02-bootsector-print/README.md +++ b/02-bootsector-print/README.md @@ -7,9 +7,10 @@ something on the screen. We will raise an interrupt for this. On this example we are going to write each character of the "Hello" word into the register `al` (lower part of `ax`), the bytes `0x0e` into `ah` (the higher part of `ax`) and raise interrupt `0x10` which -tells the machine to print on screen the contents of `ax`. +is a general interrupt for video services. -`0x0e` on `ah` is necessary to indicate tty mode. +`0x0e` on `ah` tells the video interrupt that the actual function +we want to run is to 'write the contents of `al` in tty mode`. We will set tty mode only once though in the real world we cannot be sure that the contents of `ah` are constant. Some other