why is it not printing out.. please help

[shopnobhumi]

.txt
.globl main

main:

# f= (g+h)-(i+j);

    li $s0,0
    li $t1,0
    li $t2,0
    li $s1,4
    li $s2,5
    li $s3,6
    li $s4,7

    add $t1, $s1, $s2 # sum of s1,s2 is stored in t1 or temporary variable
    t1 contains g+h

    add $t2, $s3, $s4 # sum of s3,s4 is stored in t2 or temporary variable
    t2 contains i+j

    sub $s0, $t1, $t2 # s0 gets $t1- $t2, which is (g+h)-(i+j)
    li $v0,1
    move $ao, $s0 # suppose to printf("f=%d\n",f) 
    li $v0, 10      
    syscall
#it is giving me syntax error

[wildgoose]

You have a problem with the MARS library.

li $v0,1 Print integer
mov $a0,$s0 a0 is integer
syscall <--- MISSING

li $v0,10
syscall #exit

[shopnobhumi]

You have a problem with the MARS library.

li $v0,1 Print integer
mov $a0,$s0 a0 is integer
syscall <--- MISSING

li $v0,10
syscall #exit

oh thank you but i am still getting syntax error while trying to load on PCSpim as it is saying problem with line where it says .globl main

[shopnobhumi]

i meant to say it is not running

[shopnobhumi]

here is the code but it is giving me syntax error on function main. Can anyone tell me why please

.txt
.globl main

main:
# f= (g+h)-(i+j);

    li $s0,0
    li $t1,0
    li $t2,0
    li $s1,4
    li $s2,5
    li $s3,6
    li $s4,7

    add $t1, $s1, $s2 

    add $t2, $s3, $s4 

    sub $s0, $t1, $t2 
    li $v0,1
    move $a0, $s0
    syscall
    li $v0, 10
    syscall 

[wildgoose]

I downloaded the PCSPIM simulator and it doesn't like the system calls or the .txt label. I typically use a real MIPS processor, with real tools. Were you instructed to use this simulator, and where did the sample program or the control syntax of your sample program come from? I see no reference to those declarations in PCPSIM's help file!
And no MARS library reference.

[wildgoose]

Okay, had to get away from it, download and read the Appendix A document, twiddle and retry. It ran. Answer -4.
I also tabbed the text as normally it isn't suppose to be in column 1 but not sure if that was it or not!

.text
.align	2
.globl	main

main:
# f= (g+h)-(i+j);

	li $s0,0
	li $t1,0
	li $t2,0
	li $s1,4
	li $s2,5
	li $s3,6
	li $s4,7

	add $t1, $s1, $s2 

	add $t2, $s3, $s4 

	sub $s0, $t1, $t2 
	li $v0,1
	move $a0, $s0
	syscall

	li $v0, 10
	syscall