This is a simple "Hello World" application for BIOS development.

bioshello.s

.code16
.text

/* 
This is a simple "Hello World" application for BIOS development.
This code prints the ASCII character 'A' on the serial interface at 0x3f8 
Compile with: 
i386-elf-as -o bioshello.o bioshello.s
i386-elf-ld -o bios-256k.elf -T ldscript.ld bioshello.o
objcopy -O binary bios-256k.elf bios-256k.bin

And test in QEMU with:
qemu-system-i386 -M isapc -bios bios-256k.bin -d in_asm -vga std -serial stdio

Disassemble with:
i386-elf-objdump -mi386 -Maddr16,data16 -D bios-256k.elf

LD Script contains:
SECTIONS {
    . = 0x0;
    .text : { *(.text) }
}

*/
.org 0xa000
entryPoint:
mov    $0x41, %al
mov    $0x3f8, %dx
out    %al,(%dx)
jmp    entryPoint

.org 0xfff0
actualEp:
ljmp   $0xf000,$entryPoint
.ascii "10/06/20"
.byte 0x0
.byte 0x0
.byte 0x0