Consider an 8G-byte memory board built from 1G-byte memory chips (1G=230). How m
ID: 641252 • Letter: C
Question
Consider an 8G-byte memory board built from 1G-byte memory chips (1G=230). How many address lines go into the board? How many data lines go into the board? What is the size of the decoder used on the chip to decode an address? How many chips are needed to build the board (assuming no error check is implemented)? What is the size of the decoder on the board? Suppose the most significant address lines are used to refer to the chip number. On which chip is the following memory location found? 1 00100000 00000000 00000000 00000000
Explanation / Answer
NOTE: i am taking the system as 8bit system
a)
Given total memory = 8G = 23* 230 = 233
hence 33 address lines are requires
b)
it is reading 1 byte at a time
hence 8 datalines are requires
c)
since we have to decode 1 byte out of 2^30 bytes on chip
we have to use 30 {230= 1G} bit decoder
hence the size of decoder = 30 X 1G
d)
we have to build 8G-byte memory using 1G-byte chips
hence 8 chips are required to build the board
e)
since we have to decode 1 chip out of 8
we have to use 3 {23= 8} bit decoder
hence the size of decoder = 3 X 8
f)
in 33bit address given to board
first 3 bits represents the address/number of the chip on board
and next 30bits represent address on the chip
hence the addres
1 00100000 00000000 00000000 00000000
belongs to chip number 5 (100 address)
{
000->1,
001->2 ,
010->3,
011->4,
100->5,
101->6,
110->7,
111->8
}