Section B: Assembly Language Programming

$(15$ marks$)$

Write a complete Wombat $2$ assembly language main and subprogram. The main program tests the subprogram: it reads in exactly one integer, checks that the integer is valid input, calls the subprogram and writes out the result. The subprogram must compute the function: $f(n)=6+nf(n-1)$ where $f(0)=4.$ The program must be properly commented.

Appendix $-$ Wombat Machine Instructions Summary

In the following description, $"c(m)"$ refers to the contents of memory location $"m",$ and $"=>"$ indicates data movement $($copy$).$

$\backslash$table$[[$Mnemonic$,$Opcode,Decimal,Description$],[$stop$,0000,0,$Stop execution$],[$load$,0001,1,c(m)=$acc