Microprocessor vs. Microcontroller-based system

I believe everybody is familiar with the term of ‘CPU’ or ‘processor’. When we discuss about purchasing a new Personal Computer (PC), laptop or notebook, the speed of the CPU will be our priority, subsequently of course its price. Thus, the performance of the CPU becomes our essential attention before deciding to buy. Microprocessor actually is another term for CPU or processor. It is just a single chip, is designed to be a brain on a motherboard and needs fan to cool its system. Even though its size is smaller than a motherboard, it is capable of reading binary instructions from a storage device called memory, accepts binary data as input and processes data according to those instructions, makes decisions and provides results as output [1]. It is a semiconductor device (integrated circuit) that is manufactured by using the large-scale integration technique [1]. It has three (3) main internal components: Register Array, Arithmetic and Logic Unit (ALU) and Control Unit (CU).

Intel 4004 First microprocessor was invented

http://en.wikipedia.org/wiki/Intel_4004

Intel Core 2 Quad 

http://www.tomshardware.com/forum/269283-28-intel-refuting-historical-inaccuracies

Figure 1

Besides the CPU and motherboard, we require a hard disc and RAM with higher capacity such as 500GB and 4MB respectively to complete our new PC. We also buy a mouse, a monitor and a keyboard. In fact, a PC is so called a microprocessor-based system or a microcomputer system. A microcomputer system consists of a CPU/processor/microprocessor, memory, input output (I/O) and bus systems as depicted in Figure 2. Bus systems compose to address bus, data bus and control bus.

Advances in semiconductor technology have developed since last 40 years, from SSI (Small-Scale Integration) to LSI (Large-Scale Integration) and it gives impact on computers certainly, from large computers to single-chip microcomputers. With the advancement of the semiconductor technology, it is possible to design a microcomputer into a single chip and so called a microcontroller.

Different types of computers are designed to serve different purposes. General purpose computer is a type of a microprocessor-based system where the main components of a microcomputer system are designed separately. Its functions can be simply changed by changing a program [3]. Followings are the example of microprocessor-based system applications.

¡  PC/laptop/notebook/netbook

¡  Mainframe - powerful computers used primarily by corporate and governmental organizations for critical applications, bulk data processing such as census, industry and consumer statistics, enterprise resource planning, and financial transaction processing.

http://en.wikipedia.org/wiki/Mainframe_computer

¡  Workstation

   - high-end microcomputer designed for technical or scientific applications. Intended primarily to be used by one person at a time, they are commonly connected to a local area network and run multi-user operating systems. The term workstation has also been used to refer to a mainframe computer terminal or a PC connected to a network. http://en.wikipedia.org/wiki/Workstation

http://www.b2net.co.uk/sun/sun_blade_2500_workstation.htm

¡  Server - physical computer (a hardware system) dedicated to running one or more such services (as a host) to serve the needs of users of the other computers on the network.

http://en.wikipedia.org/wiki/Server_(computing)

¡  Supercomputers

 - used for highly calculation-intensive tasks such as problems including quantum physics, weather forecasting, climate research, molecular modeling (computing the structures and properties of chemical compounds, biological macromolecules, polymers, and crystals), and physical simulations (such as simulation of airplanes in wind tunnels, simulation of the detonation of nuclear weapons, and research into nuclear fusion).

http://en.wikipedia.org/wiki/Supercomputer

Microcontroller-based system is a special-purpose computer system designed to perform a dedicated function [2]. It is also known as embedded system. Unlike a general-purpose computer, microcontroller-based system/embedded system perform one or a few predefined tasks [2]. Followings are the example application of microcontroller-based system.

·         Household equipment – washing machine, microwave, heater, air-conditioning system

·         Lab equipment

·         Mouse, modem, keyboard

·       Car controller system – automatic gear transmission, suspension system, steering controller system etc.

·         Industrial process control

Comparison between microprocessor-based system and microcontroller-based system[4]:

Microprocessor-based system		Microcontroller-based system
Advantages	Disadvantages	Advantages	Disadvantages
Flexible design	Required other peripheral devices to fully function	Less peripheral devices	Limited memory
Expandable input or output port	Costly for small system	Low cost	Limited input output ort
Expandable memory	Longer time to construct	Easy to learn and less time to construct
	So many instruction set (code)	Less instruction set
		Flexible design

Both microprocessor and microcontroller-based system consist of a microcomputer system. However, it is not difficult to differentiate them. Microprocessor-based system is built with separate parts of hardware and its physical still the same as a PC even it becomes a server or else. While microcontroller-based system physically is not the same as a PC anymore, it becomes a microwave, washing machine etc. which performs specific function only. Microcontroller itself contains a microcomputer system on its IC.

References :
[1]          R. Gaonkar, The Z80 Microprocessor : Architecture, Interfacing, Programming and Design. Columbus, Ohio, USA: Merrill Publishing Company, 1988.
[2]          H.-W. Huang, HCS12/9S12 An Introduction to Software and Hardware Interfacing. Clifton Park, NY, USA: Delmar Cengage Learning, 2006.
[3]          M. M. i. A. Zabidi, Modul Pengajaran Mikropemproses 68000 Bahasa Himpunan & Rekabentuk Sistem. Skudai, Johor,Malaysia: UTM, 1998.
[4]          A. M. Omar, "Short Course on Peripheral Interface Controller (PIC)," unpublished|.

Written by:
Siti Sara Binti Rais

‘My Earliest Rock Band’

Jika disebut ‘The Dark Side of the Moon’ pada masa sekarang, kebanyakan orang mungkin terfikirkan filem terbaru Transformers. Namun masih segar dalam ingatan itulah album pertama dari kumpulan Pink Floyd yang saya dengar pada usia mentah 9 tahun lebih 20 tahun yang lalu. Pengaruh minat abang-abang saya terhadap minat saya untuk lagu-lagu genre rock ternyata besar dan kesannya masih saya rasai hingga ke hari ini.

Antara faktor-faktor utama yang saya rasa merupakan daya penarik kumpulan tersebut adalah lirik-liriknya yang puitis, melodinya yang inovatif serta karakter ahli-ahli kumpulannya yang pelbagai ragam.  Ditubuhkan pada 1965, ahli-ahli kumpulan Pink Floyd bertukar-tukar sehinggalah pada tahun 80an namun ahli kumpulan yang paling saya minati adalah David Gilmour, pemain gitar, komposer serta antara penyanyi utama kumpulan itu. Saya rasa tidak salah jika dikatakan kumpulan Pink Floyd ini amat berpengaruh dalam menukar lanskap industri muzik pada masa itu. Mereka telah menjual lebih dari 200 juta album di seluruh dunia (wikipedia.com).

Seniman malaysia yang saya rasa dipengaruhi oleh Pink Floyd adalah M. Nasir kerana kebanyakan lagu beliau berentak seperti kumpulan tersebut.

David Gilmour pada tahun 1970an

Mungkin ketika saya kecil saya tidak memahami sepatah pun maksud liriknya namun saya rasa masih dapat menghayati alunan muziknya. Deringan loceng, degupan jantung dan alunan lunak gitar Gilmour dalam ‘breathe’ masih menjadi lagu yang saya minati di dalam album ‘The Dark Side of The Moon’.

"Breathe"

Breathe, breathe in the air
Don't be afraid to care
Leave but don't leave me
Look around and chose your own ground
For long you live and high you fly
And smiles you'll give and tears you'll cry
And all you touch and all you see
Is all your life will ever be
Run, run rabbit run
Dig that hole, forget the sun,
And when at last the work is done
Don't sit down, it's time to dig another one
For long you live and high you fly
But only if you ride the tide
And balanced on the biggest wave
You race toward an early grave.

Oleh: Mohd Suhaimi Sulaiman

Leakage Reduction Technique: MTCMOS

In modern high performance integrated circuits, more than 40% of the total active mode energy can be dissipated due to the leakage currents [1]. With more transistors integrated on die, leakage currents will soon dominate the total energy consumption of high performance ICs. The sub-threshold leakage current is one of the most dominant leakage current components [1]. It is the drain to source leakage current when the transistor is off, i.e, the applied voltage Vgs is less than the threshold voltage Vt of the transistor (weak inversion mode). The subthreshold leakage current in short channel MOSFET can be expressed as follows [1]

Where Io is the drain current with Vgs =Vt. The subthreshold current depends on the transistor parameters as listed in Table 1 [2].

Parameter	Dependence
Transistor Width (W)	Directly proportional
Transistor Length (L)	Inversely proportional
Temperature (T)	Exponential increase
Transistor Threshold Voltage (Vt)	Increase by an order of magnitude with 100mV decrease
Input Voltage (Vgs)	Exponential increase

Portable battery operated devices that have long idle times are particularly affected by this leakage power loss. Existing designs must therefore be modified in a way that it curbs the draining of battery current when it is not operational.

A popular low leakage circuit technique is the Multi threshold Voltage CMOS (MTCMOS) .This technique is based on disconnecting the low threshold voltage logic gates from the power supply and/or the ground line via cut off high threshold sleep transistor is also known as “power gating”. Several MTCMOS circuit techniques have been proposed by considering many costs such as energy overhead, wake up delay, voltage, current and etc.

Multi threshold voltage CMOS (MTCMOS) reduces the leakage by inserting high threshold devices in series to low Vth circuitry [2]. In an MTCMOS circuit as shown in Figure 1, all of the logic transistors have low threshold voltages to enhance circuit speed. In order to suppress the high subthreshold leakage current characteristics of the scaled low threshold voltage transistors, high threshold voltage switches are added between the low threshold voltage logic circuits and the power supply and ground lines [3]. These high threshold voltage power supply and ground switches are controlled by a sleep signal. A sleep control scheme is introduced for efficient power management. During the active mode of operation, the sleep control switches are activated, providing a virtual power and ground line for the logic circuits. Since their ON resistances are small, the virtual power and ground line almost functions as real power line. During the standby mode, these high threshold voltage sleep control switches are turned off, reducing the subthreshold leakage current. This technique is also called power gating.

Figure 1: Schematic of MTCMOS circuit

      In fact, only one type of high Vth transistor is enough for leakage control. Figure 1(b) and (c) shows the PMOS insertion and NMOS insertion schemes respectively. The NMOS insertion scheme is preferable, since the NMOS on resistance is smaller at the same width; therefore it can be sized smaller than corresponding PMOS. The effect of an on resistance NMOS sleep transistor in series with a low Vth circuit can be approximated very accurately by replacing the high Vth device with a single linear resistor, R as shown in Figure 2. During normal circuit operation, the virtual ground node is close to real ground, so Vds of the sleep transistor is small and the resistive approximation is very accurate .

Figure 2: Sleep Transistor modelled as resistor

With the continous scaling of CMOS devices, leakage current is becoming a major contributor to the total power consumption. In current deep-submicrometer devices with low threshold voltages, subthreshold and gate leakage have become dominant sources of leakage. Power gating techniques have become very common in literature and in practice, and MTCMOS implementations in particular have demonstrated significant improvements in standby power consumption.

Written by :
Nordiana Mukahar

References:

[1] Stan, M.R.; Barcella, M., “MTCMOS with outer feedback (MTOF) flip-flops,” Proceeding of the IEEE International Symposium on Circuits and Systems, pages 429 - 432, May 2003.

[2] Kao, J.; Chandrakasan, A.; Antoniadis, D., “Transistor Sizing Issues And Tool For Multi-threshold Cmos Technology,” Proceedings of the 34^th Design Automation Conference, pages 409-414, June 1997.

[3] Volkan Kursun,; Eby G. Friedman.; “Multi-voltage CMOS Circuit Design,” pages 75-77, 2006.

Daylighting-Renewable Energy System

KLIA

Bukit Raja Shopping Mall

Before the invention of the electric lighting, natural light played a very important role in people’s life. They used daylight to read, write and to do all kinds of work. The use of natural lighting was then forgotten after the advent of the electric bulb. However, the oil crisis forced many people to look for alternative energy sources. Ever since, the use of daylight is becoming increasingly popular especially in building sector.

Daylighting is one of renewable energy sources besides biomass and hydro-power. It actually refers to the practice of placing windows or other openings in a building so that the natural light can give effectual internal lighting. Thus, relying on daylighting can minimize energy consumption in building for lighting and cooling purposes. Daylighting technology such as light pipe is being used widely in western countries but the acceptance in Malaysia is still limited. Here in Malaysia, the Malays apply the concept of daylighting in designing their traditional Malay houses. They do not use artificial lighting during daytime and their house has many windows, which are open in daytime but closed during night.  Nonetheless, they used the curtain to protect heat and gleam from the windows. Consequently, the daylight cannot transmit into the interior.

There are many advantages of using daylighting for interior lighting. Daylighting offers a good money saving strategy. Secondly, daylighting can be used as a supplement to replace some part of lighting system. Natural sunlight is free; therefore it will reduce the operating costs.

Relying on daylighting could reduce the energy consumption for lighting purposes in building. When using daylight, it will reduce of using electricity for the owners of the building.     

After that, daylighting can be used to supplement a lighting system or even replace some system besides giving satisfactory view of the external environment and provide a healthier indoor environment. Healthier environment will improve work productivity.

Some examples of the modern buildings in Malaysia that maximize the use of natural light for interior lighting are Kuala Lumpur International Airport (KLIA), Kuala Lumpur City Center (KLCC) and an atrium at Bukit Raja Shopping Mall, Klang.

Written by:

Nurul Huda Kamarulzaman

Norlaily Abdul Rashid

Shahidatul Maslina

Albert Einstein

source of image: th.physik.uni-frankfurt.de

Secara umumnya, nama Albert Einstein tidak perlu diperkenalkan lagi. Teori yang paling diingati ialah E = mc ²,  formula yang berjaya mengangkat nama Einstein setanding dengan cendekiawan sains yang lain. Di sini, dicoretkan sedikit sebanyak sejarah mengenai kehidupan Einstein sebagai santapan minda semua. Einstein dilahirkan di Ulm, selatan Jerman pada 14 March 1879 – 18 April 1955. Bapanya  Hermann Einstein merupakan seorang jurujual yang juga merupakan seorang jurutera. Bapa dan ibunya bekerja di sebuah syarikat bernama Elektrotechnische Fabrik J. Einstein & Cie, yang merupakan sebuah syarikat yang berasaskan kepada produk elektrik.

Semasa kecil, Einstein tidak berupaya bertutur sehingga berumur tiga tahun dan dipercayai menghidap sejenis penyakit yang berkaitan dengan autisme. Einstein memulakan zaman persekolahannya sewaktu berumur 5 tahun di sekolah Catholic elementary school.  Minat Einstein dalam bidang fizik bermula apabila sewaktu kecil, bapanya telah memberikan sebuah  kompas kepadanya. Beliau berfikir bagaimana jarum kompas boleh bergerak.  Seiring dengan peningkatan usianya, beliau telah membina banyak model-model yang telah menunjukkan bakatnya dalam Matematik. Beliau sering membaca buku-buku berkaitan sains dan matematik seperti Critique of Pure Reason and Euclid's Elements dimana Einstein menggelarkannya sebagai "holy little geometry book” walaupun usia baru menjengah 10 tahun. Sifat ingin tahu yang kuat disamping kerajinannya telah membawa kepada satu era baru dalam bidang sains.

Beliau merupakan seorang warga Jerman yang telah menemukan teori kerelatifan. Teori ini telah membawa satu revolusi yang besar dalam bidang fizik, matematik dan kejuruteraan. Berdasarkan pencapaiannya, Einstein telah dianugerahkan sebagai bapa fizik moden dan telah menerima hadiah Nobel dalam bidang Fizik pada tahun 1921.

 Kajiannya mengenai kesan fotoelektrik dan teori kuantum telah memasyhurkan nama beliau dalam bidang fizik. Einstein telah menerbitkan lebih daripada 300 jurnal saintifik disamping 150 jurnal bukan saintifik dan pelbagai jenis buku yang berkaitan dengan sains. Sepanjang kariernya, beliau pernah bertugas di pelbagai universiti seperti  University of Bern, Karl Ferdinand University di Prague dan Humbolt University of Berlin sebagai pensyarah dan profesor.

Einstein mati pada pukul 1.15 pagi, 18 April 1955 di Hospital Princeton di New Jersey. Mayat beliau dibakar pada hari yang sama tanpa sebarang adat istiadat di Trenton, New Jersey mengikut hasratnya. Walaupun beliau telah pergi meninggalkan kita semua namun, ilmu-ilmu dan pengetahuan yang ditinggalkan tetap akan kekal dan digunakan  hingga ke akhirnya. 

Disediakan oleh:

Nurul Huda Kamarulzaman

Siti Musliha Nor Al-Din