Vannevar's Law is named after the mid-twentieth century engineer, Vannevar Bush, named after his first name because Bush's Law refers to the discredited supply-side economic policy pursued in the United States of America and the United Kingdom in the last few years of the New Elizabethan Era. It states the following:
"Information Technology develops linearly and incrementally and specialisms tend to be isolated. Revolutions and competition are rare".
The rate of progress in IT is sometimes contrasted with that in space-related industries, where progress is seen as exponential, frequently revolutionary and highly competitive.
Note For Readers In The Gordon Timeline
Although this is possibly the most significant difference between OTL and the Caroline timeline, those living in the timeline do not generally see an alternative, just as we see no alternative to Moore's Law. Hence the following explanation is from OTL's perspective, though it excludes the POD itself.
Limits On The Progress Of Information Technology
- Moore's Law did in fact apply in terms of doubling of transistors per unit area of silicon or germanium for a short period in the 1960s. However, it went unnoticed and hence did not become a target for industry or research. This was a factor in its decline and rate of change has long since become linear.
- Higher rates of economic inflation means that there is less demand for hardware. People buy devices to last because profit and wages are constantly undermined by inflation. However, this has only been the case since about 1986.
- Due to the difficulty in manufacturing integrated circuits, IBM tends to monopolise hardware simply because it's the largest IT company. Other companies simply lack the resources to compete. This stifles innovation. Other monopolies in IT hardware also exist. IBM are the only manufacturers of useable microprocessors and a number of decisions have been made within the company which have slowed technological change.
- Several nations in the developed world have a state monopoly on telecommunications. This has led to a situation where telecommunication subscribers rent their computers from the PTT or Post Office. This situation has, however, only existed since the use of online data services became popular. It entails that subscribers are generally unable to upgrade their hardware until the organisation from which they rent it chooses to do so.
- Engineers, mathematicians and logicians have failed to find any way of connecting circuits consisting only of any particular single kind of logic gate to express all possible truth tables, i.e. there are no known Sheffer functions in the formal logical systems used in this timeline, although of course they do exist undiscovered and in fact are known to philosophers and in informal logic. The connection between their use in one field and the other has, however, never been recognised. This single fact is the most important scientific and technological difference between the Caroline Era and OTL. Two major consequences is that many types of logic gates are composed of circuits which cannot be realised by combinations of any other logic gates, and that there are often no known ways to simplify the design of a higher-level logic circuit without changing its function.
- In connection with the fact above, De Morgan's Laws' are not known to mathematicians, logicians or engineers in this timeline, though they are again familiar in philosophy and informal reasoning. This again means that there is often no way to simplify a higher-level logic circuit.
Taken together, these two facts mean that although the level of integration of transistors initially progressed exponentially, it did not reap the rewards it has in OTL, because it was easily possible for a circuit with the same function to have something like ten times the number of transistors, making it both larger and slower than its better-designed equivalent in OTL.
- Due to these constraints, IBM designed the influential IBM 7030 differently. They began to design it earlier and therefore used an earlier design of transistor, chose to save space and money by standardising on a byte of six rather than eight bits and were unable to use pipelining or prefetch due to the lack of space and the lost efficiencies in the circuits that would have been required. Hence all of IBM's mainframes were larger, more expensive and slower.
- Computer-aided Design is primitive, not particularly user-friendly and short cuts are often missed. This is in itself because digital computers are less advanced.
- The lower processing speed means that the distances travelled by signals on printed circuit boards and within integrated circuits are not a bottleneck and they have not needed to be addressed in designing hardware.
- IBM did not design capacitor-based dynamic RAM chips because more effort and money was needed to design its other hardware. All semiconductor RAM is therefore static and consists of flip-flops made from the larger components required, so their capacity is lower per transistor than even the static RAM chips in OTL. This makes a microcomputer with the same specifications larger and more expensive.
- Software is sometimes rather slower because shortcuts in logic using functional completeness or De Morgan's Laws are not used, and because the likes of brute-force algorithms or optimising loops by unrolling them would take up unacceptably large amounts of memory. However, precisely because of the lack of space and slower processing, optimisation for speed and memory is better than it is here and there is little software bloat or creeping featurism.
- Engineers and other professionals tend to enter careers in Space technology rather than IT because it is seen as more glamorous and lucrative. Hence there is a "brain drain" into the space industries which holds back IT.
- Vannevar Bush's conservatism with respect to technological progress, particularly his statement about a computer the size of the Empire State building, has been quite influential, partly because of the disappointing influence of miniaturisation on IT, and has become a self-fulfilling prophecy in the Caroline timeline in the same way as Moore's Law has in ours.
As a result of Vannevar's Law, analogue computers to do the same tasks lasted longer and some aspects of contemporary technology are still analogue where they would be digital had Moore's Law applied. One example is the Apollo Guidance Computer.