def read_pod_raw(pod, page_start, npages, raw_bytes):
    """Reads npages number of pages from pod, returns
    initial raw bytes combined with bytes read"""
    if npages < 1:
        raise AttributeError('Number of pages cannot be less than 0')
    if npages > 15:
        raise AttributeError('Number of pages cannot exceed 16 (8192 bytes)')
    page_size = 512
    adr = page_start * page_size
    nbytes = npages * page_size
    response = pod.read_flash(adr, nbytes)
    response = response[4:-2]
    datab = response.encode()
    for i in range(npages):
        start = i * page_size
        end = start + page_size
        raw_bytes = raw_bytes + datab[start:end]
    return raw_bytes
