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Chapter 4 - Introduction to Matrix Intercom Systems 49
As you can see in Table 4.1, while a ten-user system “only” requires 100 crosspoints for
all possible communications paths, a 100-user system requires 10,000 crosspoints. Now,
realize the number of crosspoints has a direct correlation to power consumption, physical
size, and cost. It becomes apparent that with a traditional architecture, crosspoint matrices
have a pretty small limit on maximum practical size.
When McCurdy Radio Industries introduced their 9500 series matrix intercom product, 50
ports required a rack frame 3 RU in height, and weighed 20 pounds. At the time, the size
limitation was understood, but not regarded as a problem because it was thought that no
one would ever need more than 50 users in a single intercom matrix. Today, we can look
back and put that statement in the same category as IBM’s assertion in the 1950’s that “the
world market for computers is 5 systems – TOPS,” or the apocryphal Bill Gates quotation
to the effect of, “Who will ever need more than 640K of memory?” In 1985, the market for
systems as large as a 50-user intercom was primarily limited to the major television
networks.
Table 4.1
Number of Users vs. Number of Crosspoints
Number of Users Number of Crosspoints
10 100
25 625
50 2,500
100 10,000
200 40,000
400 160,000