Question and Answere

Q1. Discuss different types of cache mappings.

Ans:
Direct, Fully Associative, Set Associative.

Q2. Discuss the size of the cache memory on the system performance.

Ans:



Q3. Discuss the differences between EDORAM and SDRAM

Ans:
EDO RAM



SDRAM



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Questions and Answers

Q1. Discuss the various control signals in a typical RAM device (say HM626)

Ans:



/OE: output enable bar: the output is enables when it is low. It is same as the read bar line
/WE: write enable bar: the line has to made low while writing to this device
CS1: chip select 1 bar: this line has to be made low along with CS2 bar to enable this chip
Q2. Download the datasheet of TC55V2325FF chip and indicate the various signals.

Ans:






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Questions And Answers

Q1. Enumerate the similarities and differences between the Microcontroller and Digital Signal Processor

Ans:
Microcontrollers usually have on chip RAM and ROM (or EPROM) in addition to on chip i/o hardware to minimize chip count in single chip solutions. As a result of using on chip hardware for I/O and RAM and ROM they usually have pretty low performance CPU. Microcontrollers also often have timers that generate interrupts and can thus be used with the CPU and on chip A/D D/A or parallel ports to get regularly timed I/O. The prime use of a microcontroller is to control the operations of a machine using a fixed program that is stored in ROM and does not change over the lifetime of the system. The microcontroller is concerned with getting data from and to its own pins; the architecture and instruction set are optimized to handle data in bit and byte size.

Digital Signal Processors have been designed based on the modified Harvard Architecture to handle real time signals. The features of these processors are suitable for implementing signal processing algorithms. One of the common operations required in such applications is array multiplication. For example convolution and correlation require array multiplication. This is accomplished by multiplication followed by accumulation and addition. This is generally carried out by Multiplier and Accumulator (MAC) units. Some times it is known as MACD, where D stands for Data move. Generally all the instructions are executed in single cycle. These DSP units generally use Multiple Access and Multi Ported Memory units. Multiple access memory allows more than one access in one clock period. The Multi-ported Memory allows multiple addresses as well Data ports. This also increases the number of access per unit clock cycle.

Q2. Name few chips in each of the family of processors such as: Microcontroller, Digital Signal Processor, General Purpose Processor

Ans:
Microcontroller: Intel 8051, Intel 80196, Motorola 68705
Digital Signal Processors: TI 3206711, TI 3205000
General Purpose Processor: Intel Pentium IV, Power PC


Q3. Enlist the following in the increasing order of their access speed
Flash Memory, Dynamic Memory, Cache Memory, CDROM, Hard Disk, Magnetic Tape, Processor Memory


Ans:
Magnetic Tape, CDROM, Hard Disk, Dynamic Memory, Flash Memory, Cache Memory, Processor Memory

Q4. Draw the circuit of an anti-aliasing Filter using Operational amplifiers


Ans:



Q5. Is it possible to implement an anti-aliasing filter in the digital form?


Ans:
No it is not possible to implement an anti-aliasing filter in digital form. Because aliasing is an error introduced at the sampling phase of analog to digital converter. If the sampling frequency is less than twice of the highest frequency present the higher signal frequencies fold back to lower frequency band and hence can be distinguished in the digital/discrete domain.

Q6. State with justification if the following statements are right (or wrong)
Cache memory can be a static RAM
Dynamic RAMs occupy more space per word storage
The full-form of SDRAM is static-dynamic RAM
BIOS in your PC is not a Random Access Memory (RAM)


Ans:
Cache memory can be a static RAM right
The cache memory need to have very fast access time which is possible with static RAM.

Dynamic RAMs occupy more space per word storage wrong
DRAMs are basically simple MOS based capacitors. Therefore occupy much lower space as compared to static RAMs.

The full-form of SDRAM is static-dynamic RAM wrong
SDRAM is Synchronous Dynamic RAM.

BIOS in your PC is not a Random Access Memory (RAM) Wrong
The BIOS is a CMOS based memory which can be accessed uniformly.


Q7. Explain the function of the following units in a general purpose processor
Instruction Register
Program Counter
Instruction Queue
Control Unit


Ans:
Instruction Register: A register inside the CPU which holds the instruction code temporarily before sending it to the decoding unit.

Program Counter: It is a register inside the CPU which holds the address of the next instruction code in a program. It gets updated automatically by the address generation unit.

Instruction Queue: A set of memory locations inside the CPU to hold the instructions in a pipe-line before rending them to the next instruction decoding unit.

Control Unit: This is responsible in generating timing and control signals for various operations inside the CPU. It is very closely associated with the instruction decoding unit.

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Question and Answers

Q1. What are the Hierarchical components in a embedded system design.

Ans:




Q.2. What is LVDS?


Ans:

Known as Low Voltage Differential Signaling. The advantages of such a standard is low noise and low interference such that one can increase the data transmission rate. Instead of 0 and 5 V or ±5V a voltage level of 1.5 or 3.3 V is used for High and 0 or 1 V is used for Low. The Low to High voltage swing reduces interference. A differential mode rejects common mode noises.

Q.3. Is there any actuator in your mobile phone?


Ans:

There is a vibrator in a mobile phone which can be activated to indicate an incoming call or message. Generally there is a coreless motor which is operated by the microcontroller for generating the vibration.

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Questions and Answers of Real Time Embedded Systems

Q1. Give one example of a typical embedded system other than listed in this lecture. Draw the block diagram and discuss the function of the various blocks. What type of embedded processor they use?

Ans:
Example 1: A handheld Global Positioning System Receiver





A GPS receiver receives signals from a constellation of at least four out of a total of 24 satellites. Based on the timing and other information signals sent by these satellites the digital signal processor calculates the position using triangulation.

The major block diagram is divided into (1) Active Antenna System (2)RF/IF front end (3) The Digital Signal Processor(DSP)

The Active Antenna System houses the antenna a band pass filter and a low noise amplifier (LNA)

The RF/IF front end houses another band pass filter, the RF amplifier and the demodulator and A/D converter.

The DSP accepts the digital data and decodes the signal to retrieve the information sent by the GPS satellites.

Q2. Discuss about the Hard Disk Drive housed in your PC. Is it an RTES?

Ans:



Hard drives have two kinds of components: internal and external. External components are located on a printed circuit board called logic board while internal components are located in a sealed chamber called HDA or Hard Drive Assembly.

The big circuit is the controller. It is in charge of everything: exchanging data between the hard drive and the computer, controlling the motors on the hard drive, commanding the heads to read or write data, etc.

All these tasks are carried out as demanded by the processor sitting on the motherboard. It can be verified to be single-functioned, tightly constrained,
Therefore one can say that a Hard Disk Drive is an RTES.


Q3. Elaborate on the time-to-market design metric.


Ans:

The time required to develop a system to the point that it can be released and sold to customers. The main contributors are design time, manufacturing time, and testing time. This metric has become especially demanding in recent years. Introducing an embedded system to the marketplace early can make a big difference in the system’s profitability.


Q4. What is Moore’s Law? How was it conceived?

Moore's law is the empirical observation that the complexity of integrated circuits, with respect to minimum component cost, doubles every 24 months. It is attributed to Gordon E. Moor, a co-founder of Intel.



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Questions and Answers

Q1 Which of the following is a real time embedded system? Justify your answer
(a) Ceiling Fan
(b) Microwave Oven
(c) Television Set
(d) Desktop Key Board
(e) Digital Camera
Ans:
(b) and (e) are embedded systems
(
(a) Ceiling Fans: These are not programmable.
(b) & (e) obey all definitions of Embedded Systems such as
(i) Working in Real Time (ii) Programmable (iii) A number of systems coexist on a single platform to discharge one function(single functioned)
(c) Television Set: Only a small part of it is programmable. It can work without being programmable. It is not tightly constrained.
(d) Desktop Keyboard: Though it has a processor normally it is not programmable


Q.2 Write five advantages and five disadvantages of embodiment.
Ans:
Five advantages:
1. Smaller Size
2. Smaller Weight
3. Lower Power Consumption
4. Lower Electromagnetic Interference
5. Lower Price
Five disadvantages
1. Lower Mean Time Between Failure
2. Repair and Maintenance is not possible
3. Faster Obsolesce
4. Unmanageable Heat Loss
5. Difficult to Design

Q3. What do you mean by Reactive in Real Time. Cite an example.
Ans:
Many embedded systems must continually react to changes in the system’s environment and must compute certain results in real time without delay. For example, a car’s cruise controller continually monitors and reacts to speed and brake sensors. It must compute acceleration or deceleration amounts repeatedly within a limited time; a delayed computation could result in a failure to maintain control of the car. In contrast a desktop computer system typically focuses on computations, with relatively infrequent (from the computer’s perspective) reactions to input devices. In addition, a delay in those computations, while perhaps inconvenient to the computer user, typically does not result in a system failure.