Just out of curiosity, when you say your target is i486, do you mean that you are targeting x86 with only the instructions that existing prior to the Pentium, or do you mean you are testing on actual 486 PC hardware? I am guessing the former, as the majority of 486 systems have long since ceased working, and were never as common as later system would be.
Also, are intending for your final system to run in real mode, or is the use of Turbo Pascal primarily related to your intended bootloader compiler? Turbo Pascal for DOS 7 (which dates from 1992 - I recall using it at the time - and was the last TP release before they renamed it to Delphi in 1995) does not produce 32-bit code, AFAIK, though I may be wrong about that. Conversely, the Windows version, called Borland Pascal for Windows, doesn't produce either 16-bit real mode or 32-bit protected mode - it was exclusively 16-bit protected mode for Windows, as the majority of systems at the time were 286 systems, and Win32S hadn't been released yet. To the best of my knowledge, none of the versions of Turbo Pascal/Borland Pascal/Delphi that generate 32-bit code can generate stand-alone executables - there are Mac and Linux versions of some of the later Delphi compilers, but they aren't going to work for OS dev.
It's blink. So, i'm remember GDI.
Double buffering is my friend?