CPU 8086
ORG 0x2000

;Load a file and print it

;Set the stack
cli
mov sp, stack + 0x100
sti

;Check for an empty tail
cmp byte [si], 0x0
je error

;Find the end of the filename and add a null if needed
;Set DI at the tail
mov di, si
findend:
;Check for the string end
cmp byte [di], 0x0
je load
;Check for a space
cmp byte [di], 0x20
je addnull
inc di
jmp findend
addnull:
mov al, 0x0
stosb

;Load and print the file
load:
;Load
mov bx, stack + 0x100
mov ah, 0x0
int 0x22
;Check for errors
cmp al, 0x1
je error
;Print
mov si, stack + 0x100
mov ah, 0x0
int 0x21

int 0x20

error:
mov si, errormsg
mov ah, 0x2
int 0x21
int 0x20

;Data
errormsg db "File not found", 0x0

stack:
 