Justin Lloyd's Thinkering

Somebody needs to think about this stuff...

Better date format

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If I write my dates backwards, year, month, day, and time (using the numbers 0 to 23 to represent the hours of the day), when I sort them, they sort from earliest date & time to latest date & time.

Read – Danny Dunn, Invisible Boy

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Today I finished reading “Danny Dunn, Invisible Boy” by Jay Williams

Update from the adult Justin: This was the first book I read in the Danny Dunn series, and I devoured them all in any order I could get them.

This was also the very first book I checked out of the public library on a brand new library card from the Penarth public library.

I also learned, a few weeks later, I had the power to fill out a little rectangular card with up to a half-dozen book titles, and have them brought from another library somewhere else in the country directly to my local library so that I could read them.

Infinite loops

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Is it possible for the CPU in my Atom to figure out if the CPU is in an infinite loop?

Is there something I can do to test this?

For the infinite loop I mean?

I can easily test for $100 JMP $100 or in BASIC “10 GOTO 10”, or an equivalent, but how about a harder loop condition?

Word Search Game part two

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If I store combinations of letters in a lookup table, because in the English language there are letter groups that go together quite often.

So CH is a common letter group. And so is TH. And so is ING.

How many common letter groups are there?

How many would I use in all of my word dictionaries?

If a word search has a theme, say names of colours, or names of animals, would there be overlap between the same words used in different word search games?

Hrmmm.

Let’s assume I have a list of words I need for a word search level. Each word is actually just a one byte value that is an index in to a table where the real words are stored.

So we have a “word search word list table” that has a string describing the theme of the table, .e.g “COLOUR NAMES” and four bits that indicate how many words are used in that word search level.

Then I have a list of between 8 and 23 words which are just one byte values into another table that is the actual individual word.

Let’s call that other table “word table.”

That word table can contain up to 256 words.

Each word is stored as a series of six bits for a letter group along with three bits to indicate the letter of the word, i.e. how many six bits sequences make up the word.

Those six bit sequences are an index into another table called “letters” which are actually either individual letters or groups of letters.

So effectively I have to think of the English language as having 26 letters plus another possible 38 “letters” made up of two letter pairs and three letter triples. Single. Double. Treble.

Footnote: The problem I was trying to solve was how to store hundreds of words in as small an amount of memory as I can. I only had about 4KB of RAM to play around with as I recall. I wanted to store hundreds of different words, graphics and code.

Word Search Game

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I only have about 4KB of RAM to play around with as I recall.

I want to store hundreds of different words, graphics and code.

I need to pack words in to memory efficiently.

The problem is that there are 26 letters in the alphabet which takes up fives of memory.

Which is inefficient.

And I would need some complex code to decipher every five bits in a stream.

Because it is a word search I have a limited number of words to be searching for within a theme.

If I choose my words carefully so that all of the words only use 16 different letters then I can pack two letters in to a single byte.

Assume three bits to indicate word length.

But the word length value 0 through 7 is added to a base value of 3.

No word will be shorter than three letters.

So that gives me words between 3 letters and 10 letters in length.

That gives me four bits to store the first letter of the word and one bit left over.

Footnote: The problem I was trying to solve back then was how to store hundreds of words in as small an amount of memory as I can.

Frozen dessert

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I swallowed an entire ice cube earlier, and I still haven’t pooped it out. How come?

P.S. This is a joke.

Read – I Wish That I Had Duck Feet

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Today I finished reading “I Wish That I Had Duck Feet” by Dr. Seuss

I did not like this book.

I did not wish I had duck feet.

I found the premise rather odd.

It wasn’t the rhyme, nor the beat.

I just was happy with how I was, by God.

Bath-time experimentation

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The amount of water filling a glass that is tilted in the water goes down as the glass fills up. Must be because the glass becomes more upright.

The rate at which a glass moves from flat to upright as it fills up is dictated by the height of the glass.

A glass with a quantity of water in it set spinning in a bath will spin for a time from the amount of water in the glass and the size of the glass.

The size of a glass determines the amount of work to start spinning. Something to do with the glass touching the water slowing it down or making it sticky?

The size of a glass determines how quickly it will come to a rest after it has been set spinning given a fixed amount of liquid in the glass.

Bath time

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The amount of air inside an upside-down glass says how fast the glass will go up [raise] in the water.

The amount of water in an upside-down glass says how hard the glass is to lift out of the water.

The higher the water outside gets above the level of the water inside of an upside-down glass increases the amount of work required to lift the glass out of the water.

Read – Fox in Socks

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Today I finished reading “Fox in Socks” by Dr. Seuss

Update from the adult Justin: I can remember the exact day that I read this because I was given this book on my birthday and I read it that night in my bed, aloud, to my Father.

Fox in Socks and Green Eggs & Ham are still my two favourites.

A purrfect fit

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Have you ever noticed how the holes in a cat’s fur are always in the right place for them to look out of?

Jelly and the speed of light

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Forgive me for this indulgence. I was eight and a half years old when I wrote the notes below. Just typed it up from some very old notebooks. Even back then I had some weird thoughts.

So if I take some jelly and I push against it, it deforms and let’s say it’s a large square block of jelly. So if I push on one end, my finger sort of distorts the jelly which makes the other end of the jelly distort and jelly bulges out in various places. But the jelly at the far end furthest away from where my finger is pushing doesn’t distort as much because the jelly near my finger bulges outwards around it.

Also if you think about it in that case as jelly moves back and forth, jelly is just made of the same stuff that everything else is made of, metal & steel, and wood & trees and things like that.

So the far end of the jelly moves after my finger pushes, like if I drop a stone in to a pond the waves ripple out across the surface of the pond and the amount if I have very large stone, if I have a bucket of water and a very large stone and I put the stone in a bucket of water, the water level in the bucket goes up, it moves up, it rises. Meaning that the stone is displacing (is that a word?) water. If I put my finger in to jelly, my finger is displacing jelly and a stone in a bucket doesn’t displace the water instantly, just like the ripples on a pond do not happen instantly.

They travel through the water at a limited speed. This means that if I put my finger in water the amount of water on the other side of the pond also moves but by a tiny, tiny amount. And water closer to my finger moves more.

With jelly it’s the same thing, if I push my finger in to jelly, the jelly that’s closer to my finger moves more than the jelly that’s further away from my finger. I guess we can call that absorbance? Absorbing? Whatever.

But the jelly that’s furthest away from my finger also moves, but by a tiny amount but it has to move after my finger has pushed in to it.

So I have a long plank of wood, it’s made of the same basic stuff as jelly. When I push on the end of a plank of wood, this plank of wood on the workbench, and I push one end with my finger, the plank of wood moves, but the wood close to my finger is being displaced because the wood, the fibers that make it up are more rigid than the jelly, they don’t move as much, but they still have to move.

My finger is applying, what do you call it, pressure or force? What’s the difference? If there for the wood works the same way as the jelly and the water, there is a wave traveling through the plank and the wood fibers at the other end of the plank furthest away from my finger move after the wood fibers that are closest to my finger.

I’m going to assume that the more rigid a substance, jelly or wood or steel, the faster that the force of my finger moves through it. So I can actually see in a large piece of jelly when my finger is pushing against one side seeing the other side deform after my finger begins pushing. But in a piece of wood I can’t see that because it has to happen too fast.

So if I now have a steel bar that I’ve got here on the work bench and I push one end, the steel bar is harder to bend or shape than wood, which means to me that I believe that the stuff that the steel bar is made of, the metal, is more rigid than the wood fibers that are in a plank of wood, which are more rigid than the jelly stuff in a block of jelly which is more rigid than the water droplets in a pond.

If that’s the case then if there was a material like a really, really strong piece of metal or something that was completely rigid, when I push on one end, the other end would move instantly, the wave, and I have to assume there is a wave passing through the wood and I have to assume there is a wave passing through the metal just like there is a wave passing through the water, the wave would travel instantly from where my finger pushes on it to the other end.

And if you have this completely rigid piece of metal you transmit a message faster than you could see. Faster than light maybe?

Hmm.

Sounds plausible but I suspect that the universe will conspire to prevent me from doing something like that. I suspect that the stuff that makes up wood and metal and rock, that there’s no completely rigid thing, substance anywhere in the world that would allow that to happen.

So what is the difference between pressure and force?

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