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Requirement.
Second, as the control effort grows, it is quite possible that a single computer
will not be able to provide or control enough resources for the entire setup. Even
though computers are rapidly becoming more powerful, their processing power,
memory capacity, and hard-disk space will always be finite.
On top of that,
there are resources that have actually become less plentiful in modern computers
than they used to be. One example is the number of PCI slots that a modern
computer offers. This can become an issue, since a quantum computer consisting
of hundreds of qubits might require a large number of different control devices that
interface over a GPIB bus, for example. Each GPIB bus can only support about
30 devices, though. Thus, to support 100 microwave generators, the computer
needs to provide room for three or more GPIB interface cards. It is therefore very
likely that any large-scale quantum computing effort will eventually be controlled
by several different computers that perform partially complementary and partially
identical tasks. The software should be able to transparently support this. I will
call this requirement the Load-Sharing Requirement.
7.2.2 Maintainability
As the size of a software project grows, it becomes harder and harder to keep
it maintainable. If such a software project is undertaken by a group of self-taught
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