Now we know, CPU memory unit are specified by the address bus. Number visible on the address bus can transmit different information, CPU can address a number of memory cells.
It is assumed that a CPU has 10 address bus, let's look at it in addressing the situation. We know that, in a steady state computer, a wire may be transmitted only two, high or low.
Expressed in binary is 0 or 1, 10 wires can transmit a 10-bit binary data. The 10-bit binary number can represent different data it? 10 power of 2. The minimum number is 0, the maximum number is 1023.
The following figure shows a CPU 10 having address lines, the address information of binary information sent address line 10 to the memory 11 is transmitted. When think about, such as access address for the memory unit 12, 13, what buses are transmitted on the address?
一个CPU有N根地址线，则可以说这个CPU的地址总线宽度为N。这样的CPU最多可以寻找2的N次方个内存单元。
Q: CPU addressability formula?
A: 2n = addressability
Q: Why is 2n?
A: The computer is binary, there is assumed that three address lines. Variation in three binary address lines, are as follows:
000
001
010
011
100
101
110
111
From the above it can be seen in three binary address lines, eight times may vary. 3 so that the root of 2, is equal to 8.
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