If the population is sufficiently dense, so that significant amounts of protectant are released, material released from the majority which died first can protect a few of their surviving fellows. Bacteria frozen without such chemicals leak internal contents, among which are many substances that are cryoprotective. Postgate says that bacteria have apparently survived for 4,800 years in the brickwork of Peruvian pyramids, and maybe even 300 million years in coal, using the drying strategy. He also describes bacteria that apparently survived for 11,000 years in the gut of a well-preserved mastodon, although in this case the colony may have continued to live and multiply using nutrients available in the carcass. Postgate gives several other examples of long-surviving bacteria, and he is careful to mention the possibility that some of the bacterial cultures may have been contaminated, so not all of the reports are necessarily reliable.
Spores are bacterial cells in complete dormancy, with thick protective coats.
In terms of our computer analogy, a bacterial spore is like a handheld calculator that has repackaged itself into its original protective shipping carton and turned itself off. The resistance of some bacterial cells to environmental destruction is impressive. Some bacteria form resistant cells called endospores. The original cell replicates its chromosome, and one copy becomes surrounded by a durable wall. The outer cell disintegrates, but the endospore it contains survives all sorts of trauma, including lack of nutrients and water, extreme heat or cold, and most poisons.