computer.show_procs returns the percent of ram used by processes, and since the numerical amount of ram used is constant for a given process you can get an approximation of ram size from that 

get_ram_size=function()
  for line in get_shell.host_computer.show_procs.split("\n")[1:]
    line=line.split(" ")
    if line[4]!="Terminal" then continue
    return 11/(line[3][:-1].val/100)
  end for
  return null
end function