|Technology levels and steps of the incremental path|
|Level 0||side products|
|Introduction of total positional control||xxx|
|Level I||side products|
|switch-over to stiffer materials||xxx|
|Level II||side products|
|introduction of practically perfect vacuum||xxx|
|Level III|| basis for products|
The incremental path towards advanced APM systems describes a desired process of slowly increasing technological capabilities (tools making better tools) with avoidance of loss of a strong orientation towards the far term goal of the stiff nanomachinery in gem-gum technology. This translates into starting off by using soft nanomachines to the fullest to get away from soft nanomachines ASAP.
The incremental path towards advanced APM systems is complementary to the direct path. The direct path to advanced APM systems in comparison describes a desired process of jumping to the advanced far term goal ASAP without significant detours. It is specifically focused on early usage of scanning probe microscopy for mechanosynthesis of diamond (or silicon) with throughput levels that are significant enough for the bootstrapping of a gem-gum factory. Following the direct path alone may be problematic.
- Sometimes a direction that on first inspection looks like it would lead fast to the goal actually does lead to it very slowly (or even not at all).
- Sometimes a direction that on first inspection looks as if it would lead only very slowly to the goal actually would lead to the goal fastest (which might still be slow).
This was the reason for the introduction of the distinction between direct path and incremental path.
Details on the critics towards the direct path will be located on the "direct path"-page.
- modular molecular composite nanosystems (MMCNs)
- coarse-block APM systems
In Appendix II of the book "Radical Abundance"  it is proposed to go through several levels of APM technology to reach advanced (positional atomic precision & diamondoid) APM.
These levels will serve as a rough guideline for the structuring of this Wiki.
In "Nanosystems"  technology stages are mentioned beginning with section 16.5.2. (written before the emergence of structural DNA nanotechnology).
The recently developed self assembling structural DNA nanotechnology and similar reliably designable foldamer structures might be a good starting point from technology level 0. By introducing robotic (more precisely stereotactic) control one could reach something like a "block level precision robotic technology" technology level I from there in a first step. In a second step one could change to e.g. Pyrite or Silica technology level II as building material to increase structural stiffness, reduce vibration amplitudes and get thus more placing accuracy. And finally in a third step one could switch from fluid phase to vacuum so that carbon and silicon can be assembled technology level III.
This very crude temporal outline is by no means the only possible way to go.
There may be shortcuts or other paths.
Note: The definition of atomic precision does not imply single-atomic manipulation (it includes topological atomic precision without positional atomic precision). The derived term "APM" also tells nothing about product size. It is thus suitable for todays self assembly and all technology levels beyond 0. Advanced levels of APM though are capable of macromanufacturing of diamondoid structures with positional atomic precision.
Since a nanofactory at the endpoint of an incremental path will inherit the capability of handling at least the materials of one generation before it may be better to call the products gemoid instead of diamondoid this terminology would make it more clear that gemstone like bio-minerals like quartz are included.
Paths that are treated separately because its harder to find a concrete goal for them
Note that the behavior of mobile electrons at the nanoscale is not as easily predictable as the behavior of mechanics at the same scale thus there's less exploratory engineering for nanoelectronics than nanomechanics. See:
- non mechanical technology path (including nanoelectronics)
- brownian technology path. (including things like synthetic biology)
[Todo: improve article quality]
Reasons for the order of introduction of capabilities
A necessary prerequisite for the second major step (that is: going from soft atomically precise but not necessarily positionally atomically precise materials to stiffer positionally atomically precise ones) is: the first major step (that is the introduction of the capability to pick and place building blocks at featureless sites.) This is a prerequisite since stiffer building materials (like bio-minerals) are more featureless and thus uncontrollable with self assembly (or at least much harder to control).
- Slides: "Toward Modular Molecular Composite Nanosystems" -- K. Eric Drexler, PhD -- U.C. Berkeley -- 26 April 2009 -- 
- Radical Abundance: How a Revolution in Nanotechnology Will Change Civilization - by K. Eric Drexler
- Nanosystems: Molecular Machinery, Manufacturing, and Computation - by K. Eric Drexler