Start working on rom-based kernel

rom/kernel.asm

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+	cpu 8086
+	org 0x0000
+
+	db 0x55, 0xAA
+	db 0x00
+	jmp near init
+
+	times (0x18 - ($-$$)) db 0
+	dw 0
+	dw pnp
+
+pnp:	db "$PnP"
+	db 1 ; version 1
+	db 2 ; 2 * 16 length
+	dw 0 ; offset of next header
+	db 0
+	db 0 ; checksum (filled by fix-rom)
+	dd 0 ; device identifier
+	dw 0 ; manufacturer string
+	dw name ; product name string
+	db 0,0,0 ; device type string
+	db 0x20 ; device indicator, bit for "read cacheable" set
+	dw 0 ; boot connection vector
+	dw 0 ; boot disconnect vector
+	dw boot ; bootstrap entry point
+	dw 0 ; reserved
+
+	; zero for setting sreg without using reg
+zero:	dw 0
+
+name:	db "rdos", 0
+
+init:	push ds
+
+	; DS := 0
+	mov ds, [cs:zero]
+	; set entry points vectors
+	mov word [0x19*4], boot
+	mov word [0x19*4+2], cs
+
+	pop ds
+	retf
+
+	; entry point on boot, preempting disks
+	; this also doubles as entry point for reboot
+boot:	xor ax, ax
+	mov ss, ax
+	mov sp, stack
+
+	int 3
+
+hlt:	hlt
+	jmp hlt
+
+	%include "kernel/intr.asm"
+
+	align 512
+
+absolute 0x400
+	resb (0x501 - ($-$$))
+
+	; copy of the first 32 interrupt vectors
+ivt2:	resd 0x20
+
+	; 8kb stack
+	alignb 2
+	resw 0x2000
+stack: