The Computer

p.37, in Whitehall, explaining the message from space:
"It's a computer program," he said quietly.
. . .
"It's in three sections. ... The first part is a design -- or rather it's a mathematical requirement which can be interpreted as a design. The second part is the program proper, the order code as we call it. The third and last part is data -- information sent for the machine to work on."
And p.39:
"Our newest computers still work in microseconds. This is a machine that must operate in milli-microseconds [10-9s], ..."(1)
 
p.54-55, Flemming telling Judy about the computer:
"The memory is in the core and the core is held in a total vacuum to within a degree or two of absolute zero."
"Each core is built up of alternating layers ... half a thou. thick ... a complete yes-no gate circuit(2) on a spot of metal you can hardly see."
"Is that the equivalent of a brain cell?"
"If you like."
. . .
"The core's a three-metre cube. That makes several millions of millions. And there are six cores."(3)
"It's bigger than a human brain."
"Oh yes. Much bigger. And faster. And more efficient."
(1)In the 1960s a respectable super computer, with its own building and 24-hour staff, might have a speed of 106 instructions per second, as suggested, and 106 bytes of main memory. Giga-hertz clock speeds (109) became commonplace c2000 with, for example, the Intel(!) Pentium 3.
(2)Does that maybe sound more like a processing gate rather than just a memory bit?
(3)So let's say about 4×1013 brain cell equivalents. For 1961 that is a good margin over a human in terms of neuron numbers. But if the contest were in terms of synapses, it is now known to be much tighter:
There are "only" about 2×1010 neurons in a human brain. However, each neuron is connected to several thousand others on average, perhaps 1014+ synapses in total -- far higher connectivity than in electronic circuits (as of 2012). The A for A text does say "cells", that is neurons.
See Do we have brain to spare?, D. A. Drachman, Neurology 64(12) 2005 [doi] [p.med] [www]['12].