Make bootloader load both kernel and kernel config

boot/fat.asm

@@ -2,11 +2,9 @@
 %define self      0x00600 ; 1 sector
 %define fattab    0x01000 ; variable size
 %define rootdir   0x06000 ; variable size
-%define psp       (prog - 0x100)
+%define config    0x07800
 %define prog      0x07C00
 
-%define arguments (psp + 0x81)
-
 org self
 
 jmp short init
@@ -61,14 +59,12 @@ times (62 - ($-$$)) nop
 init:
   cli
 
-  ; Stack grows down from PSP + 64k
-  mov ax, (psp >> 4)
+  ; Stack grows down from 64k
+  xor ax, ax
   mov ss, ax
-  xor sp, sp
-  push sp
+  mov sp, ax
 
   ; Relocate from [prog] to [self]
-  xor ax, ax
   mov ds, ax
   mov es, ax
   mov si, prog
@@ -107,20 +103,28 @@ main:
   ; clusters start after rootdir
   mov [cluster_offset], ax
 
-  mov ax, filename
+  mov bx, prog
+
+  mov ax, kernel_name
   call load_file
   mov bp, 0x3332
   jc error
 
+  mov si, bx
+  sub si, prog
+
+  push si
+
+  mov ax, config_name
+  call load_file
+
+  pop si
+
+  int3
+
   ; restore boot drive number
   mov dl, [fdc.drv]
 
-  ; setup segment registers
-  push ss
-  pop ds
-  push ss
-  pop es
-
   ; jump into target
   jmp 0x07C0:0x0000
 
@@ -128,6 +132,7 @@ main:
 ; IN	AX	pointer to 8.3 filename
 ;	ES:BX	pointer to target area
 ; OUT	CF	flag set if error
+;	DI	file size in bytes (<64K)
 load_file:
   mov si, rootdir
   mov cx, [fdc.rde]
@@ -142,12 +147,12 @@ load_file:
   je .read
   add si, 0x20
   loop .search
+  xor di, di
   stc
   ret
 .read:
-  add si, 0x1A
-  lodsw
-  mov bx, prog
+  mov ax, [si+0x1A]
+  mov di, [si+0x1C]
   jmp read_clusters
 
 ; Read the file given by cluster number
@@ -247,7 +252,9 @@ error:
   int 0x16
   int 0x19
 
-filename:
+config_name:
+  db "RCONFIG SYS"
+kernel_name:
   db "RDOS    SYS"
 
 times (0x1FE - ($-$$)) db 0