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I gave up the real mode kernel since I always got R_386_16 truncated to fit and made a new kernel. The new kernel is running in protected mode, and booted from grub. I'm attempting to create a custom text rendering engine with adjustable fonts,but I'm stuck at changing the video mode from 80x25 to 320x200, and apparently the most trouble less way to do it is by modifying port 0x3c0. However, I cannot understand how the index works. Any help will be greatly appreciated.

Clement Poon
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  • Don't have an answer to your question, but dropped to VM86 for the same myself. – vhu May 26 '20 at 16:38
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    This may help: https://wiki.osdev.org/Drawing_In_Protected_Mode . If you insist on using direct port I/O: https://wiki.osdev.org/VGA_Hardware – Ruud Helderman May 26 '20 at 16:49
  • I already read osdev's vga hardware page, I just cant find any example about using direct io to change video mode, and I can't understand how the vga register index works. – Clement Poon May 27 '20 at 00:05
  • Does this answer your question? [Enter graphics mode without interrupts in assembly](https://stackoverflow.com/questions/21955406/enter-graphics-mode-without-interrupts-in-assembly) – Seva Alekseyev May 27 '20 at 02:52

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Ended up using the real mode method, since I'm too lazy to figure out how the index works.

Clement Poon
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