Q1. What are two senses in which the term random-access memory is used?
Q2.What is the difference between DRAM and SRAM in terms of application?
Q3. What is the difference between DRAM and SRAM in terms of characteristics such as speed, size, and cost?
Q4.What are some applications for ROM?
Problems
P1. Consider a dynamic RAM that must be given a refresh cycle 64 times per ms. Each refresh operation requires 150 ns; a memory cycle requires 250 ns. What percentage of the memory’s total operating time must be given to refreshes?
P2. Consider a dynamic memory cell (DRAM) of RC circuit assume that C=50 ff (f = 10-15) & that leakage current through the transistor is about 9 pA (p=10-12). The voltage across the capacitor when it is fully charge is equal to 4.5 volt. The cell must be refreshed before this voltage drops below 3 volt. Estimate the minimum refresh rate.
P3. How many check bits are needed if the Hamming error correction code is used to detect single bit errors in a 1024-bit data word?
P4. A common unit of measure for failure rates of electronic components is the Failure
unIT (FIT), expressed as a rate of failures per billion device hours. Another well-known but less used measure is mean time between failures (MTBF), which is the average time of operation of a particular component until it fails. Consider a 1 MB memory of a 16-bit microprocessor with 256K 1 DRAMs. Calculate its MTBF assuming 2000 FITS for each DRAM.
P5. The memory of a particular microcomputer is built from 64K 1 DRAMs. According to the data sheet, the cell array of the DRAM is organized into 256 rows. Each row must be refreshed at least once every 4 ms. Suppose we refresh the memory on a strictly periodic basis.
a. What is the time period between successive refresh requests?
b. How long a refresh address counter do we need?
Solution-Click here
Q2.What is the difference between DRAM and SRAM in terms of application?
Q3. What is the difference between DRAM and SRAM in terms of characteristics such as speed, size, and cost?
Q4.What are some applications for ROM?
Problems
P1. Consider a dynamic RAM that must be given a refresh cycle 64 times per ms. Each refresh operation requires 150 ns; a memory cycle requires 250 ns. What percentage of the memory’s total operating time must be given to refreshes?
P2. Consider a dynamic memory cell (DRAM) of RC circuit assume that C=50 ff (f = 10-15) & that leakage current through the transistor is about 9 pA (p=10-12). The voltage across the capacitor when it is fully charge is equal to 4.5 volt. The cell must be refreshed before this voltage drops below 3 volt. Estimate the minimum refresh rate.
P3. How many check bits are needed if the Hamming error correction code is used to detect single bit errors in a 1024-bit data word?
P4. A common unit of measure for failure rates of electronic components is the Failure
unIT (FIT), expressed as a rate of failures per billion device hours. Another well-known but less used measure is mean time between failures (MTBF), which is the average time of operation of a particular component until it fails. Consider a 1 MB memory of a 16-bit microprocessor with 256K 1 DRAMs. Calculate its MTBF assuming 2000 FITS for each DRAM.
P5. The memory of a particular microcomputer is built from 64K 1 DRAMs. According to the data sheet, the cell array of the DRAM is organized into 256 rows. Each row must be refreshed at least once every 4 ms. Suppose we refresh the memory on a strictly periodic basis.
a. What is the time period between successive refresh requests?
b. How long a refresh address counter do we need?
Solution-Click here