Week 1 Summary:

Computer architecture is defined as the computer as seen by assembly language programmers.So, here we will discuss which registers, among the many registers available inside a central processing unit (CPU), are accessible to assembly language programmers.

Computer organisation is defined as the computer as seen by hardware engineers. Here, we discuss the component of a computer from the perspective of hardware engineers.

There are two types of computer architectures:

1. The von Neumann architecture. It is the most popular, and used by personal computers. It is characterised by the fact that data and instructions are not separated in the memory. It is not possible to tell which one is data and which one is memory just by looking at the content of a memory location. It is the task of the instruction register and the instruction decoder inside the CPU to differentiate between data and instructions. It is worth mentioning that some instruction do contain data, which is called immediate data.

2. The Harvard architecture. It is mostly used in special-purpose processors such as the DSPs (Digital Signal Processors). It is characterised by the fact that it has separate memories for data and instruction. So, we can tell straightaway, if something is in data memory, then it must be data. If something is in instruction memory, then it must be an instruction.

Question : does this imply that the CPU of the Harvard architecture is simpler than the CPU of the von Neumann architecture?

The CPU and the memory communicates via three separate bussses

a. the data bus. It is bidirectional i.e data can move in both ways. During write : data moves from CPU to memory. During read : data moves from memory to CPU.

b. address bus. It is unidirectional from CPU to memory and contains the address in memory which CPU neeeds to access.

c. the control bus. It is bidirectional. Control moves from CPU to memory. Status moves from memory to CPU.

There are two type of instruction sets:

1. CISC (Complex instruction set computer) : a large number of instructions, and a small number of registers.

2. RISC (Reduced Instruction Set Computer) : a small number of  instructions, and a large number of registers.

As a comparison, imagine you have CPU1 which has a multiply (*) instruction and CPU2 which does not have a multiply instruction, but instead has an addition (+).

To do 5*7 = 35 on CPU1, you need only one instruction

To do 5*7 = 35 on CPU2, you need 6 instruction (5+5+5+5+5+5+5), or 4 instructions (7+7+7+7+7)

Questions :

• which one is better RISC or CISC?

• which one is faster RISC or CISC?

• does CPU2 need  to compare the two numbers, and then add repeatedly the bigger number, instead of the smaller number to get speed up?

• DSP is dominated by multiply (*) and accumulate (+) instructions. Is it the reason why RISC has been used?

Week 2 Summary :

Computers run programs. Programs implement algorithms. Algorithm is a sequence of instructions. Instruction tells the computer to move data from one place to another (memory to register, register to memory, register to register), to process data (add, sub, mul, shl, shr etc).

ALU (Arithmetic and Logic Unit) is that part of the CPU that does data processing and conversion. ALU is a multi-function unit. ALU, based on the command from processor, does different things at different times. ALU has two data inputs, one control input, and one result output. Do we need other output?

A comparison is done by a subtraction. For example, COMP A, B   , is done by A-B gives D. D can be 0, <0, or > 0. D = 0 means A = B. D < 0 means A < B. D > 0 means A > B.  From the value of D, there is no way the computer knows the comparison result just by looking at D. So, other things are required. They are the flags. Flags can be

• N (Negative) : If N = 0, then D must be positive. If N = 1, then D must be negative
• Z (Zero) : If Z = 0, then D must be non-zero (positive or negative). If Z = 1, then D must be zero
• V (overflow) : If V = 0, then there must be no overflow. If V = 1, then an overflow happens. An overflow happens when adding two positive numbers gives a negative number or adding two negative numbers give a positive number. How negative numbers are represented will be discussed later.
• C (Carry) : If C = 0, there is no carry. If C = , there is carry. A carry happens when adding two numbers of n bits give a result in n+1 bits.
• X (eXtended Carry) : like Carry, but for BDC (Binary Coded Decimal) numbers

So, to know the result of a comparison, we look at the flags.

• When N = 0 and Z = 0, the result is positive (A > B)
• When N = 0 and Z = 1, the result is zero ( A = B)
• When N = 1 and Z = 0, the result is negative (A < B)
• The case in which  N = 1 and Z = 1 should never happen (you can not have negative zero. It is just zero!

An instruction (in C language) such as i := i + 1; means the number 1 is stored in the same area as the instruction. Number one is carried by the instruction. Adding 1 to a number needs no ALU. It can be done by incrementation. An instruction that carries data is in an immediate addressing mode.

An instruction (in C language) such as const x = 12; means that the number will be stored in an area separate from the instruction. An instruction may refere this number using many ways such as an absolute addressing mode, indirect addressing mode, relative addressing mode, etc. More on addressing modes later ! .

Peta Karnaugh tidak berlaku untuk teknologi tertentu. Sebagai contoh, bila hanya tersedia multiplexer, kita justru memerlukan bentuk kanonik daftar minterm/maxterm. Bentuk kanonik sigma ataupun pi tidak lain adalah tabel kebenaran yang masih asli, tidak dikurangi cacah literalnya.

Mata kuliah ini melibatkan pemanfaatan mikrokontroler Arduino.

Security is based on a tight interaction between

(1) cryptography : the art and science of encrypting and decrypting a data/information/message/packet

(2) protocol : the rules governing interaction/communication between two parties

(3) access control : who are allowed to do what

(4) software : cryptography, protocol, and access control are implemented in software. Therefore if there is a flaw in software then the best approach in cryptography, protocol, and access control fails.

Buffer overflow (until now still used to break in a system) originated in a software flaw (it is the flaw in the programming language C).

SQL injection is a software flaw.

Cross-site scripting is a software flaw.

There is also problem of firewall rules rewriting in which rules governing the firewall may overwrite other rules resulting in allowing forbidden traffic, or forbidding allowed traffic.

Security initiative should not be done exhaustively. Absolute security is not achievable.

Take as an example, an intrusion detection algorithm, or a porn-site blocking algorithm.  A detection algorithm can be based on

(1) a feature

(2) a knowledge

In both cases, false alarm might happen. A false alarm is a situation in which the alarm is set on a wrong situation:

(1) a false positive : the algorithm detects the presence of something which does not exist

(2) a false negative : the algorithm detects the absence of something which exists

We need religion, because religion protects 5 (five) basic necessities:

(1) one’s life : religion teaches us not to kill (not to take the life of ourselves nor  others). One’s blood is sacred and not to be  shed except by the order of the court.

(2) one’s sanity : religion teach us not to drink intoxicating beverages

(3) one’s progeny (lineage) : religion teaches us not to commit adultery/fornication, so that when a baby is born, it has a definite (lawful) father and mother. A baby must only be born out of sexual intercourse committed on a  legitimate marriage relation

(4) one’s honour : religion teaches us to protect one’ honour. We are prohibited to us defamatory statements against one another. We are not allowed to call one another using insulting name.

(5) one’s wealth :religion teaches us to take one’s wealth by means of lawful business transactions, or by inheritance, or as a gift.

We have a built-in instinct to be religious.  The Koran says that in the world of the souls, our souls were asked by Allah “Am I not your Lord?”. The souls answered :”Of course You are. We have witnessed (the You are indeed our Lord)”.

This instinct is our drive to search for the Truth, to search for God.

There is also Pascal’s Wager which says that “It is better to believe that God exists rather than not, because if it turns out that God does not exist, we do not lose anything. But, if we do not believe that God exist, and it turns out that He does, then we will be in a big trouble”.

It is no problem if you do not believe in God, at the moment. It is also no problem if you have not found the True God.The Prophet Abraham is also described in The Koran as a young boy looking for the True God. First he thought that the sun was his god, then the moon, the stars etc. But the sun set. “God does not set”, Abraham said. So, those are certainly not god. The Koran does not criticise the fact that Abraham were still looking for God. On the contrary, The Koran praises him. Abraham even doubted that Allah can raise the dead.

“O My Lord, show me how Thou raise the dead”, Abraham said. Allah asked Abraham:”Have thou not believed?”. Then Abraham said “Not at all. I only want to tranquil my heart”. Then God ordered him to catch 4(four) birds whose bodies are to be separated into pieces and put on the top of the mountain, and then Abraham was asked to call the birds back, and the birds did indeed came back to Abraham.

Even though Abraham asked so many questions to Allah, Allah still calls him “The Friend of Allah”.  Abraham was a monotheist, and never he associated anything with Allah in worship. So, if you have any doubt, ask….! …search!…reason!…think! It is not sinful to ask question. It is not sinful to doubt something. It is not sinful to think and to reason.

Of course there are things we can not reason, such as the existence of the heaven, the hell, the devils, the world of the partition (barzakh), the angels, and of course, Allah Himself. These are from the world of the unseen (ghaeb). We know the world of the unseen because Allah told us by sending prophets and the books of revelation.

People (even those who do not believe in God) on a vehicle (an airplane or a ship) struck by turbulent weather will automatically pray “O God save me”. This is our instinct to be religious.

Allah never talked to us directly in this world, except to the prophet Moses (peace be upon him). Allah spoke to the prophet Muhammad (peace and blessing of Allah be upon him) in the Heaven during the Night of Journey and Ascension (Isra’ and Mi’raj).

It is not befitting for a human being that Allah speaks to him except

(1) by revelation (wahy)

(2)  or from behind the veil (min warai hijaabin)

(3) by sending the angel (yursila rasuulan)

We know that The Koran is the Truth by implication

(1) The prophet Muhammad (PBUH) was never known to be a liar. He even was given the title of Al-Ameen (The Truthful)

(2) The verses and chapters in The Koran are not known to contradict one another

(3) No human being nor jinn can compose even one verse of the same quality as that of The Koran

(4) The Koran speaks of something that had not even existed at that time (ahead of its time) and it turns out to be true latter.

(5) The Koran criticises the prophet Muhammad (PBUH) when he turned his face away from a blind man who had came to him.

A muslim means somebody who surrenders/submits to Allah’s will. A true muslim is a slave of Allah. Indeed, Islam is revealed to free human beings from the slavery of other human being. A muslim testifies that “There is none worthy of worship but Allah, and Muhammad is the final prophet, His slave and His messenger”.

Allah created human being in order to

(1) worship Him (in Arabic, the word ebaada - worship, has the same root as the word aabed - slave)

(2) to become His viceroy (Khalifa)  in this world

( 3) to fill the world with activities

I prefer discussion with the students. This course is not an indoctrination. There is no compulsory in religion. Everyone is free to embrace any religion he/she wishes. Of course, the risk, if any, is your own.

(1) why do we need a religion? why do we need to be religious? can we live without embracing any religion?

(2) do you believe in the Hereafter? the Heaven? the Hell? etc. If the answer is yes, what are the reasons? If the answer is no, what are the reasons?

(3) do you believe in God? what is a god? what qualities a god must possess to become The True God?

(4) why do we become muslim? because our parents are muslims? because we were born,and  brought up in a muslim neighbourhood?  why?

(5) are you sure that Islam will give you salvation in the hereafter?

(6) do you know Muhammad (PBUH)? have read the story of his life? do you believe in him? why? have you met him?

(7) do you believe that The Koran is the words of God? or is it just a book written by Muhammad? Have you read The Koran? If not, how can you believe/ disbelieve in it?

(8) do you perform the five obligatory prayers? do you understand what you say during the prayers? If not, why you keep saying something you do not understand?

(9) what is the purpose of our being created by Allah

(10) why we are here on the Earth? for what purpose?

We live twice and we are deed twice.  We we disbelieve in Allah — kaifa takfuruna billahi, while we were :

(1) before we were born, we were dead   – amwaatan

(2) after we were born, we are alive — ahyaakum

(3) one day, we will die — yumeetukum

(4) then, we will be resurrected — yuhyeekum - on The Day of The Religion (yaum al-deen)

(5) then, to Allah, all us will return  — ilaihi turja’oon

Long time ago, the radius of the earth (a very huge ball on which we live!!). The story is written here :

Allah said to The Prophet Noah (peace be upon him) : build the ark (ship) (ishna’ al-fulka) under My supervision (bi a’yuninaa)  and My inspiration (wa wahyinaa) and stop  speaking to me (wa laa tukhothibni) on behalf of those who are wrongdoers (alladziena dholamu minhum). Verily they will be drown in the flood (inna hum muqraqun) .

So, Noah build the ship . His people mocked him because it is strange to build a ship in a place very far from the sea. What is it for. What they fail to see was that it was actually a sign that a very big flood is to happen. They continued to mock him. And Noah kept building his ship until he time came. He and his followers were saved from drowning. It is narrated that rain happened for 40 days and 40 night and flooded the Earth with water. No one was exempted from the disaster, except those who were saved by God. Even Noah’s son was drown in the flood.

Noah said to his son : “O my beloved son (yaa bunayya), ride the ship (irkab) with us (ma’anaa)!” . But his son has faith in his own and said : “I will go to the top of the mountain (sa awiy ila al-jabal) that will protect me from the water (ya’shimuni min al-ma’a). And Noah told him that “No one is save from Allah on that day( laa ‘ashima al-yaum min Allahi)

Allah is rabb (Lord or teacher or educator). He taught (‘allama) Adam the names (al-asmaa’a) all of them (kullaha). He also taught (‘allama) mankind (al-insaana) what (maa) he is not (lam) knowing (ya’lam). Please not that Allah taught (past tense) and mankind is not knowing (present tense). So we are alwys ina state of not knowing about something.

So Allah is the best in teaching. Adam knows the names of everything only because Allah taught him.

There is no other way that Adam may know the names except by Allah. The angels do not know the names because Allah does not teach the angel about the names. The angel said :”Glorified You (subhanaka) . We know nothing (laa ‘ilma lanaa) except what You have taught us (illa maa ‘allamtana). Verily (innaka) You are Most Hearing (al-Sami’)  Most Knowledgeable (al-’Aliem).

Dzu al-Qarnain (Owner of the two horns) said :”Give me (aatuni)  iron ore (zubar al-hadied) until they are as high as the two hills (hatta idza saawa baina shodafaini) . then set it on fire (anfukhu hatta idza ja’alahu naaran) , then pour on it copper (aatuni ufrigh alaihi qithra).

Dzu al-Qarnain built a wall made of a mixture of iron and copper to protect the people from the Ya’juj and Ma’juj (these are the evil people and the wrongdoers - mufsiduna fi al-ardl).  Dzu al-Qarnain realised that his ability to build the wall is from Allah and he realised its shorcomings as he said “When it comes the time the promise of Allah, then the wall will crumble down”.

Noah is an example for the scientists who do something which most people consider of no practical and economic values (building a ship in a place far from the sea), but when it come the time for a killer application then the values becomes very high (like a ship during a flood).

Dzu al-Qarnain is an example for the engineers who built practical things right at the time when they are needed and solve human problem straight away.

What are our problems today? If you are an engineer, then you should devise a solution for the problems : ignorance (lack of educatiion), illiteracy, poverty, backwardness,  etc.

If you are a scientist then you have to have a vision and start today pave the way to the solution of the problem of tomorrow. No engineer will be able to solve a problem without having scientists in the past discovered the laws and principles to be incorporated in the solution of tomorrow’s problems.

Everything starts with a vision. The Prophet Joseph (pbuh) first saw a vision that he saw eleven stars, the sun, and the moon all prostated to him.

(1) hardware : piranti keras komputer, misalnya CPU (Central Processing Unit, memory (RAM, ROM< flash disk), LCD monitor, keyboard, mouse, dsb.

(2) software : piranti lunak komputer, misalnya sistem operasi (MS Windows, Linux, Mac OS, Android), program aplikasi (MS Office, Libre, dsb), browser (Internet Explorer, Safari, Firefox, Chrome), dsb.

(3) network : jaringan, misalnya, Wi-fi 802.11, Wimax 802.16, Zigbee 802.15.4, bluetooth, infrared, dsb.

(4) user : manusia pengguna komputer

(5) procedures : peraturan-peraturan penggunaan kompute, misalnya UU ITE (Undang-undang Informasi dan Transaksi Elektronik)

(6) data : yang diperoleh melalui piranti input komputer

Dari ke 6(enam) komponen di atas, yang dinamakan teknologi informasi adalah no (1), (2), dan (3). Nomor  (1) s/d (5) semuanya akan cepat usang (obsolete), sedangkan no (6) tidak pernah usang. Data selalu mempunyai makna bila kita tempatkan pada suatu konteks. data yang ditempatkan pada suatu konteks dinamakan informasi.

Tujuan utama sistem informasi adalah koleksi data. Data kemudian diproses menjadi informasi. Informasis elanjutnya diproses menjadi knowledge. Knowledge diproses menjadi wisdom.

Alasan itulah yang mengakibatkan Google, Facebook, dsb. menyediakan layanan gratis. Google, selain search engine, juga menyediakan sarana penterjemahan, Google office, Google map, dsb. Baik Google maupun Facebopok tidak meremehkan data kita, walau kita meremehkan data kita.

Berikut adalah beberapa hukum-hukum terkait teknologi informasi:

(1) Hukum Moore (diambil dari nama Gordon Moore, co-founder dari perusahaan integrated circuit Intel) mengatakan bahwa setiap 18 (delapan belas) bulan akan muncul CPU (Central processing unit) baru yang densitas komponennya 2x lebih padat, serta kecepatannya 2x lebih besar.

Hukum Moore mengakibatkan hardware pasti menjadi usang (outdated) setelah 18 bulan. Ini berakibat pada keputusan investasi pengadaan peralatan komputer yang harus memperhitungkan Hukum Moore.

(2) Hukum Metcalfe (diambil dari nama Robert Metcalfe, co-inventor dari NIC - Network Interface Card, dan  co-founder dari perusahaan 3Com) mengatakan bahwa manfaat yang diperoleh oleh seseorang yang bergabung dengan suatu jaringan yang telah memiliki N-1 anggota, adalah berbanding lurus dengan N(N-1)/2.

Hukum Metcalfe mendasari layanan-layanan gratis di Internet, dan dapat menjelaskan mengapa filosofi open-source dapat berjalan sekalipun banyak software open-source yang didistribusikan secara gratis.

(3) Hukum Murphy mengatakan bahwa “if anything can happen, it eventually will” , bila sesuatu dapat terjadi, maka, cepat atau lambat, akan terjadi juga.

Hukum Murphy meminta kita untuk secara periodik mengganti password atau PIN (personal identification number) dan kita gunakan password yang kuat, bukan password yang mudah ditebak. Hukum Murphy juga meminta kita membuat backup dari file-file yang kita punya, agar bila satu media hilang/tidak dapat diakses/datanya rusak dsb. kita masih memiliki salinannya.

Leavitt’s Diamond dan McKinsey 7S

Leavitt Diamond menggambarkan interaksi timbal balik yang sangat erat antara 4 (empat) hal : teknologi,  proses bisnis, user, dan struktur organisasi. McKinsey 7S adalah semacam Leavitt’s Diamond tetapi memiliki 7(tujuh) komponen : ..

Leavitt’s Diamond menggambarkan bahwa perubahan teknologi berakibat pada perubahan proses bisnis (misalnya, transaksi berbasis SMS, email, ATM), user harus beradaptasi, dan perubahan peraturan. Sebaliknya user yang berbeda juga perlu teknologi yang berbeda (misalnya disabled user dg user dg fisik yg normal; user yang educated dg yang kurang memperoleh pendidikan). Proses bisnis yg berubah dapat pula menuntut perubahan teknologi, user, maupun peraturan.

Implementasi IT bukanlah untuk IT itu sendiri. Saya meyakini bahwa IT memfasilitasi tidak hanya koleksi data, pemrosesan data menjadi informasi, tetapi juga pemrosesan informasi menjadi knowledge, serta pemrosesan knowledge menjadi wisdom, Oraginsasi yang memiliki wisdom akan lebih unggul dibandingkan yang tidak.

Knowledge ada dua macam : 1. tacit knowledge, berujud pengalaman dan belum dituliskan 2. explicit knowledge, pengetahuan yang tertulis.