BASIC DRAM SYSTEM

BASIC DRAM SYSTEM


In principle, the function of DRAM is very simple. It requires only
writing the data into a certain address, preserving it for a
certain period of time, and reading the data out. We trace this
simple function using the diagram shown in Fig. 6. In the
read operation, the memory chip needs to set up the address
data. In DRAM, in contrast with other memory technologies,
a unique address input scheme is adopted. With the address
multiplex scheme, the address data are divided into two portions,
defined as row address and column address, respectively.
According to the enable-address signals, each address
is stored in an address input buffer by individual timing.
Therefore, the number of address pins is equal to one-half of
the whole address digits. On the other hand, two sequential
address inputs are necessary. After obtaining the address in-

formation, the stored data, which are selected by the row address,
are read by sense amplifiers to amplify the signals.
Then, the column address is used to transmit the amplified
signals to the output buffers. In the write operation, a write
amplifier allows reversal of the data on the I/O bus, if the
input data are different from the data on the I/O bus.