This is what our professor said:

As a matter of fact, NAND and NOT(invertor) are fundamental to LSI.
Such qualities of NAND as speed or power consumption depend on NMOS. Those makers who can provide excellent NMOS are at present only five – Intel, TSMC, Samsung, Toshiba and Texas Inc., among over 1000 CMOS makers.
The five can produce LSI only with NAND and NOT. Others need NOR, which are not effected much by NMOS’ quality.

“This textbook,” he said, “explains first NOR and then analogically NAND, because the writer of it have been working in other maker than the five.”

Especially Intel has a special technlogy to produce LSI mostly with high-speed NMOS and few pMOS, called “dynamic circuit”.

And he said again to the student, “You have to thank for those people, who let you enjoy Playstation.”


NOR in CMOS Logic

NOR in CMOS Logic can be discussed just reversely to NAND.

The truth table for NOR is as below.
Truth table for NOR

In the case only both inputs are zero, the output is positive.

The important feature of NOR circuit is, nMOS are arranged parallel and pMOS are serial.
Truth table for NOR

It’s a beautiful symmetry, though I always forget that pMOS opens when its input is zero (and its drain is grounded) .

Automatic Instruction

In order to learn English, I had believed until recently that the most important ablity would be reading, and then writing – if you couldn’t hear someone, you could beg him to repeat it slower.

I remember when I was in a concert of a guitarist Steve Howe in a small club in Tokyo. It was more than ten years ago. He was talking on the stage, but I couldn’t understand him, for he spoke so fast. Then I said to him loud, “Steve! Will you speak more slowly?”. The audience laughed, but Steve was very kind to say “OK!” and then started to speak slowly.
This heart-warming episode had made me confirmed with my idea.

But recently I have found, that there are so many automatic instructions by voice, like help systems by telephone, podcasts, recorded guidances in exhibitions, etc. It’s difficult, or not flexible, to ask them to repeat or play slowly. Though I still believe reading is most important, I have started to think that listening should be put more weight on.

NAND in CMOS Logic

Below is a circuit diagram of NAND in CMOS logic.
NAND in CMOS logic

The circuit is made of two pairs with nMOS and cMOS, each of which has a common input, A and B, respectively.
Actually two points of a common input should be drawn to branched from the same source, nonetheless such branches are omitted to simplify the diagram.

This arrangement is explained by the truth table.
Truth table of NAND

The above table is not written in HTML, but a located pict file, because I didn’t like to take a trouble in showing a “bar” above “A·B”.

The table shows only when all inputs to nMOS and pMOS are positive the output will be zero.
This is realized as the picture below shows.
NAND, A=0, B=0
(The figure above has been replaced on 9/28)

As the figure above indicates, no charge is supplied to pMOS and all charges are lost to the ground through nMOS, the output comes to 0.
As a matter of fact, when all inputs to nMOS are positive, the output will be zero, whatever inputs to pMOS would be, because all charges will lost to the ground.

In other case, for example, when only the input to B is zero, the out put will be positive, because the current passes one pMOS of the two arrayed parallel, and is kept from being lost lost at one nMOS of the two arrayed serial.
NAND, A=0, B=1

Another example is when all inputs to nMOS and pMOS are zero the output will be positive. In this case all pMOS are open and the current flows, but the output isn’t affected by the number of open pMOS, because they are arranged parallel.
NAND, A=0, B=0

Based on some of these examples, the below is what is to be remembered about NAND in CMOS logic.

nMOS: serial, pMOS: parallel

No history of programming languages

Yesterday I spent all day long to write an article about history of programming languages.
It was only 4 pages that I had to write, but I had a difficulty to summary the content properly.

When I had started to write it last week, I had sought in Amazon for books about it, written by any authorities. To my surprise, I found very few, Japanese or English.
First I used a keyword “History of programming”, and then changed it to “History of computing”. At last I found only one exactly with that title ( in English ) and ordered it.

Two days later the book was delivered (great Amazon!) . It was about how to study history of computing systematically…a methodology (isn’t it?).
That book taught me that it would be yet a delicate matter to discuss a history of computing. One of the reasons is that computers are used in so many fields, that the goal of computing is quite ambiguous. Or a some technology of computing may succeed technologically and other commercially.
Now I have understood, why books of such a title have been scarcely published.

Or only I was not smart at searching for books?


Yesterday I took all day long to write an article to send my editor until today. I went to bed at an usual time, and woke up early as usual (I like to get up early), looked over my article once again, and just sent it by e-mail.

From now on I will have free time for a while. Today I will go to the University (for an adult, it is classified as “free time” to go to the school to learn), and then I will start a lot of things I would have been longed for doing.

Before that I have to wake my husband up and make breakfast. It’s easy, just to warm milk and heat toasts. He has always only a small appetite.

Sweets for the deceased

Yesterday I explained about special kind of sweets that people in Japan set in front of graves, or in the room, for Buddhist ceremony. Today I took a picture of some examples which I found in the shop where I buy daily items every day.

Sweets in package, for graves

Usually they are block of dried starch paste, mixed with sugar, brightly colored.
In the picture they looked shiny. They are all packed in transparent plastic containers, in order to keep ants out.