There has more and more big size (> 21”) display monitor in the marketing, some of the
user might not put on horizontal (width > height) and will change to vertical (height >
width). We have some specific product also shipping with the monitor fixed on vertical
mode like cashier system.
In OS environment, user can through graphics driver to change the display setting, it can
rotate to the correct angle what user use and can be control by user.
In pre-OS environment, some of monitor mount with G-sensor, therefore BIOS can aware
current display is put as horizontal or vertical and output the display correctly, like the post
logo or BIOS setup or any other post message.
Some of unit would like to save the G-sensor cost and can use GPIO pin to achieve that,
but the limitation is that cannot be dynamitic change and need to lock down the mode
(Horizontal or Vertical) before the product shipping since it cannot be changed (like
cashier). This design only can apply on the unit that has fixed the monitor and cannot be
Without G-sensor or GPIO to report the correct mode, and user does not put the monitor
as normal use case therefore the screen during BIOS post cannot show up correctly, if
user would like to check post message or boot into setup mean that will be a big problem
Creative Commons License
This work is licensed under a Creative Commons Attribution-Share Alike 4.0 License.
INC, HP, "POST SCREEN ROTATION BY HOTKEY", Technical Disclosure Commons, (January 24, 2021)