Image from Steve Bowers

Neumann vecs replicating near Dactyl. Many von Neumann self-replicating systems reproduce by creating miniature copies of themselves which then grow larger over time.

Most people watched them through the feeds of course, tapping in every now and then from the comfort of their virches. But I've had a strong fascination with Neumanns, for me the feeds were constant. Over the years I did little else but watch them work from orbit, my augmented senses drinking in the data. We'd brought a couple of thousand of them with us, each one little bigger than a lobster. They flew from our craft in drop pods barely bigger than their own bodies. Ninety-eight percent survived re-entry, well within expected parameters. We dropped them in small packs and singletons at landing sites distributed across the barren world; far enough apart to give each other breeding room but close enough to cooperate once they'd set up.

Those first few years were slow and steady. They grazed and dug and roamed, spawning little ones that would do the same. For a while it was just the generalists but specialisation came, bringing diversity. Small bots that burrowed, tiny bots that buzzed through the air, and larger models that would grow big enough to scrape quarries in megaseconds. I watched as they went from disparate packs to clusters of early civilisation. Little mechanosystems of solar trees, transport tubes and fab-houses. They grew like insect hives made up of hundreds of species. The ground was pocketed with living tunnels, cillia undulating on their walls to transport raw materials to the surface. Giant beetle-like Neumans sat next to storage towers, their probiscis' sucking down raw material to process in their specialist organs. The refined mattercache they produced was distributed among the ever growing, ever gravid workforce.

After the first pockets of industry were established the population began to explode. Thousands became millions, millions became billions. From our orbit we could have seen the progress with our biological eyes if we had them; it was like silver fungus growing on an apple. Each night the cities of industry would grow further, dropping spores way outside their borders that would blossom into mechanical life before connecting to the main. It wasn't long before resources were increasingly reallocated from growth to the terraforming proper. There were hundreds of billions of them now and the surface of the planet was encrusted with manufactories and infrastructure. Thousands of fusion generators pumped energy into the ground to melt the permafrost. Channels, dug by billions of bots, directed the water to excavation sites. There the work of trillions more geosculpted seas to our aesthetic preferences (the models there were amphibious and kept working even as the first floods came). Bioforges synthesised soil, biota, seeds and basic life that countless machines laid across continents. From my lofty view it was like watching a plague of locust in reverse, swarming over a dead land and leaving it alive.

After mere decades the planet was prepared enough that we could move into the cities (so simple compared to the rest of the efforts they were thrown up in the last megasecond, as though an afterthought). There were tens of billion continuing the work of nursing the world from its nascent biosphere to one as rich as Old Earth, but the vast majority of the mechanosystem had been dismantled. No longer necessary it was recycled. My fellow colonists barely gave it a moments thought. But in all the centuries I lived there I could never forget the majesty and the awesome power of those Neumann swarms.

Excerpt from Tyrol's Travel Notes: Terraformers

A classification system of von Neumann replicators

1. Self-assembling systems can assemble working copies of themselves from finished, manufactured components delivered to the self-assembler, or selected by the assembler from a storage location. Note; John von Neumann's original though experiment about a self-replicating system concerned a device of this sort.
2. Self-reproducing systems can manufacture all the parts necessary to reproduce themselves, but the raw materials need to be delivered to the reproducer in prepared form. Such raw materials (feedstock) may include pure liquids, plastic, mineral, carbon or metal powders, metal bar, wire, coil, sheets or ingots. Atmospheric gases and other abundant fluids may be collected from the environment, but other fluids need to be supplied.
3. Self-replicating, autotrophic replicator systems can search for, refine and process their own raw materials. They must be competent enough to collect enough material from the environment to maintain their own systems in working order, and also to reproduce working copies of themselves.
4. Self-replicating universal assemblers can gather the raw materials to manufacture copies of themselves, and also to manufacture other goods and infrastructure.
5. Self-replicating, evolving universal assemblers can respond to the environment by evolving, either by selection of the fittest or by smart or sentient self-redesign.
6. Natural self-replicating systems have emerged spontaneously via abiogenesis and evolution, and include terragen lifeforms, alien lifeforms and a range of prebiotic or non-biotic life-like processes.

• Assembler
• Asteroids and Asteroid Mining
• Bicameral von Neumann Machine Architecture
• Distributed Intelligence
• Early Vec and Neumann Development
• Goo
• Nauri
• Paste - Text by Steve Bowers
  Swarm devices manufactured by a forge system, (such as a bioforge or nanoforge) so that the individual units do not carry the code for their own replication (human red blood cells are an example of this in biology).
  
• Perpetua Project, The
• Von Neumann Probe - Text by Anders Sandberg in his Transhuman Terminology
  A Von Neumann Machine able to move over interstellar or interplanetary distances and to utilize local materials to build new copies of itself. Such probes are used to set up new colonies, perform megascale engineering or explore the universe (see the Far Edge Party).
  
• Von Neumann Sculpting