Page 209 - DCAP108_DIGITAL_CIRCUITS_AND_LOGIC_DESIGNS

Digital Circuits and Logic Design

Notes bus, the memory space could be divided into 4096 blocks of 1M. This could be implemented using
simple decoding devices.
Many real systems employ a combination of the above decoding techniques. For example,
several small devices may reside in the same block by using partial address decoding within
that block.

Self Assessment

Multiple choice questions:

1. Shifting a register content to left by one bit position is equivalent to........................
(a) division by two (b) addition by two
(c) multiplication by two (d) subtraction by two
2. Data can be changed from special code to temporal code by using ....................... .
(a) shift registers (b) counters
(c) combinational circuits (d) A/D converters
3. How many flip-flops are required for mod–16 counter?

(a) 5 (b) 6
(c) 3 (d) 4
4. Block address decoding is the merger of ........................ address decoding and full address
decoding.

(a) completely (b) partial
(c) Both (a) and (b) (d) None of these
5. Electronic semiconductor memory technology can be split into two main types or categories,
according to the way in which the memory ....................... .
(a) operates (b) runs

(c) stable (d) None of these

11.5 Semiconductor Memories

Semiconductor memory technology is an essential element of today’s electronics. Normally based
around semiconductor technology, memory is used in any equipment that uses a processor of
one form or another.
Indeed as processors have become more popular and the number of microprocessor controlled
items has increased so has the requirement for semiconductor memory. An additional driver
has been the fact that the software associated with the processors and computers has become
more sophisticated and much larger, and this too has greatly increased the requirement for
semiconductor memory. In view of the pressure on memory, new and improved semiconductor
memory technologies are being researched and development can be very rapid. Nevertheless,
the more mature semiconductor memory technologies are still in widespread use and will
remain so for many years to come. In addition to these new applications such as digital cameras,
PDAs and many more applications have given rise to the need to memories. Accordingly,
it is not uncommon to see semiconductor memories of 8 Gbyte and much more required for
various applications.

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