## RAM

 Question 1
In comparison with static RAM memory, the dynamic RAM memory has
 A lower bit density and higher power consumption B higher bit density and higher power consumption C lower bit density and lower power consumption D higher bit density and lower power consumption
Digital-Logic-Design       RAM       ISRO-2007
Question 1 Explanation:
DRAM (Dynamic Random Access Memory)
→ DRAM stands for Dynamic Random Access Memory. It is used in most of the computers. It is the least expensive kind of RAM. It requires an electric current to maintain its electrical state. The electrical charge of DRAM decreases with time that may result in loss of DATA.
→ DRAM is recharged or refreshed again and again to maintain its data. The processor cannot access the data of DRAM when it is being refreshed. That is why it is slow.
SRAM (Static Random Access Memory)
→ SRAM stands for Static Random Access Memory. It can store data without any need of frequent recharging. CPU does not need to wait to access data from SRAM during processing. That is why it is faster than DRAM. It utilizes less power than DRAM.
→ SRAM is more expensive as compared to DRAM. It is normally used to build a very fast memory known as cache memory
 Question 2
How many 128×8 bit RAMs are required to design 32K×32 bit RAM?
 A 512 B 1024 C 128 D 32
Digital-Logic-Design       RAM       ISRO-2017 May       Video-Explanation
Question 2 Explanation:
Step-1: RAM size required is 32Kx32 bits
= 32x1024x32 bits. [Note: 1k=1024 bytes]

Step-2: Given RAM chip capacity is 128x8 bits
Step-3: Required size/Given size
=(32*1024*32) / (128*8)
=1024
 Question 3
If each address space represents one byte of storage space, how many address lines are needed to access RAM chips arranged in a 4 x 6 array, where each chip is 8K x 4 bits ?
 A 13 B 15 C 16 D 17
Digital-Logic-Design       RAM       ISRO CS 2014       Video-Explanation
Question 3 Explanation:
From the given data
Each chip size is = 8K x 4 bits = 23 x 210 x 22 == 215 bits = 212 bits
Given chip array = 6 x 4 = 24 ( 24=16 and 25=32)
So the number bits required for the total chips are 5 bits.
So, total number of bits required = 12 + 5 = 17 bits
There are 3 questions to complete.

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