Best posts made by Trumpetb

@Shifty

I dont disagree with you in principle but the issue is, more than half the computers in the world are carrying errors many are carrying several errors many of which may take years to appear.

The argument here that we are discussing is that the computer will always obey the program that the human has inputted because thats what computers do. They execute lines of code as programmed.

Except they dont, that is a wrong statement. They simply appear to execute lines of code correctly for most of the time.

Never in the history of Intel computing have computers ever executed the code the programmer inputted and compiled.

The computer makes a copy of the code in RAM memory and executes that copy. It is fairly common for there to be a corruption in that copy, so you have a fail right there.

The truth is even if the copy is a good one, the computer does not execute the program correctly every time due to other errors that exist elsewhere.

And the computer cannot spot most errors it has to rely on checksums which dont reveal much and errors can cancel out in checksums.

There are several places where corruption of the program is likely to occur.

I can name several kinds of errors and in every case the program the human inputted is not followed by the computer.

FYI I worked as a second line support and a third line technical support engineer with Hewlett Packard working in Intel products SUN systems, coms and telecoms.

I designed and built several servers, designed and built a clustered supercomputer on Linux, I programmed distribution software for Hewlett Packard, I acted as an advisor to technical support companies and worked with Radio Networking companies.

I can tell you now computers do not always execute programs correctly due to fundamental issues in the way they are constructed configured and operate.

Check out Real Time computing and the ADA system

Ada is a strongly typed programming language that enjoys widespread use within the embedded systems and safety-critical software industry.

ADA solves some of these issues that plague intel systems

Computers were too unreliable for use on the Moon shot and NASA had to commission a new real time system that guaranteed that their computer would execute code correctly. NASA invented real time computing.

They would not have had to do that if computers executed code reliably and correctly but they didnt and still dont.

The only systems that do execute code correctly are real time systems, these are mission critical systems like air traffic control systems where lives are at risk or lost if code is not executed correctly.

I do know what I am talking about here.

Why do you think the most common fix for a computer is and always has been "turn it off and on again", it is because they often dont function correctly and they dont execute code correctly and turning them off and on again refreshes the OP sys the RAM images etc etc etc, for a few hours until the next error hits.

So does a computer execute code exactly how it was told to do in the code.

No - no way. Sometimes they do sometimes they dont.

@J-Jericho

excellent post you are absolutely right

Put simply, a cmos logic gate is in essence a flip flop based upon a 3.5 volt threshold

The problem is there is no such thing as a logic circuit outputting logic 1 or logic 0.

There are instead analogue circuits that output a range of voltages that we can force to behave like logic circuits.

If the voltage output of the logic circuit or gate is higher than 3.5 volt it is a logic 1 if it is less than 3.5 volts it is a logic 0. 3.5 volts has been adopted in CMOS as the threshold for logic 1

CMOS gate values are supposed to be either 0 volts or 5 volts for those logic states, but they rarely are because they are analogue circuits trying to behave like digital circuits, so we use threshold values to detect the logic states.

In realty there could be any value between those voltages and given losses in the circuits a logic 1 of above 3.5 volts could be pulled down below 3.5 volts due to a voltage sink of some kind and become a logic 0.

Then the logic has changed when it should not have changed and the computer program has then malfunctioned.

The logic state should really be unknown if the voltage in the gate output voltage is less than the 3.5 volt threshold set for logic 1, but almost 3.5 volts.

When does a 0 become a 1 at what voltage 3.50 3.49. 3.48

What happens if a gate output is at the 3.5 volt threshold and rippling slightly between 3.4 volts and 3.6 volts.

This is the computer logic equivalent of panicking.

The detection of 3.5 volts or more causes downstream logic gates to flip due to logic 1 being detected but less than 3.5 volts causes the downstream logic gate to a flop to logic 0

There is a period of indecision due to logic gate ripple where the gates are all in an indeterminate state during the ripple and they take a period of time to settle into the final state of correct logic.

The larger the number of gates the longer it takes for the ripple through and to settle

This period of settling in which the logic gates are performing illogically grows as circuits are miniaturised and with greater miniaturisation comes greater difficulty of determining logic 1 in any single gate.

The hope is of course that all logic gates will settle correctly to the correct logic value however as you quite rightly point out losses due to miniaturisation plus abnormalities can disrupt the logic gate performance.

We cannot wait forever for logic circuits to settle so we make assumptions that within a set period of time all rippling will have ceased and logic circuits will have reached the correct values.

A typical 4 logic gate cluster takes 300 ps to settle, we need not explore the ramifications of this, it is not much time, 300 trillionths of a second, but compounded by the sheer total number of logic gates in a system means that it actually can take a significant amount of time for all rippling to cease in all the gates.

This is one of the limiting factors on the growth of computer systems

After rippling has ceased we then read the output of all the gates allowing time for all rippling to end plus x, - a safety margin time. We cannot risk reading a logic gate output if it is still rippling.

But what happens when a passing neutrino enters a logic gate and trips a gate from logic 1 to logic 0 during the safety margin wait state.

Rippling must begin again. This passing neutrino could also by the way on the hard drive stab a binary value in a stored program changing the program forever and preventing the computer from obeying the designed code, because the code has now changed and is no longer as programmed.

We are bombarded by Neutrinos every day and most pass through us harmlessly but when a neutron interacts with the semiconductor material, it deposits charge, which can change the binary state of the bit and Neutrinos can only be stopped by lead or concrete so computers are vulnerable to them in stored programs in RAM in ROM and in the data carried on the bus.

We may then finish up reading the logic output during a new rippling state caused by a neutrino attack. We then have a 50 50 gamble that the logic is in error.

Exactly as you describe and pointed out J.Jericho.

And exactly as you suggest greater miniaturisation makes this effect more likely as gates miniaturise more, but neutrinos do not miniaturise and their effects could become more profound for logic circuits as we miniaturise more over time.

The more logic gates you have the more opportunity there is for Neutrino disruption.

This is a very long post I know but we are deep diving here into complex areas that usually are hidden from the general public and largely unknown to them.

The present state of miniaturisation of logic is called VLSI very large scale integration and it brings issues that are difficult to address relating to robustness and reliability of these very large scale integrated circuits.

I am comfortable J.Jericho that you already know all of this and more besides, possibly more than I do on this topic given your excellent posts.

We are in examining this topic very close to the cutting edge of computing and its far reaching implications for the future of computer systems as we plod ever onwards down the road of greater miniaturisation and with greater miniaturisation comes greater risk of failures due to the very miniaturisation that we seek.

I intended this post to illustrate exactly why your post is technically correct and on topic. I do not intend to slight other members very few people understand this stuff, and we can only know what we know.

Most members know lots of stuff I do not know and cannot hope to know and I want to make it quite clear that not knowing this deeply technical and difficult subject is no reflection on them at all.

Moores law says computer gates double in complexity every 2 years. I would suggest that Risk doubles along with that.

I am not at all surprised that most people do not know all this it is the province of micro electronics engineers largely hidden from the public and there is no need for the public to know these things only electronics engineers chip designers and systems designers need to know this stuff.

What does surprise me on a daily basis is how reliable computers are given their huge vulnerability to errors and mishap.

Computers seem to me to fly less like an F15, and more like a bumble bee, they just manage to get there despite being a bit poor at flying.

Dizzy Gillespie: "Some days you get up and you put the horn to your chops and it sounds pretty good and you win. Some days you try and nothing works and the horn wins. This goes on and on and then you die, and the horn wins."

Who is to say whether on those days when the horn won the mouthpiece was not clocked advantageously, or the gap was not providential or the mouthpiece was a little loose in the receiver or something else we now accept as really helping was not applied.

All we have is our sound, and if something helps whether that be a known adjustment or a psychological crutch I dont care, it works out the same to the audience.

More than likely this is an effective adjustment.

If it helps use it.

All that matters is reliably discovering what really does help.

@barliman2001 Wise words

It is I am convinced a power thing mixed in with being seen to be sensitive to everyone and respectful of all customers regardless of good sense.

These people as you say think they are in a dictatorship and they have to protect everyone for their own good, or they have to feel they are in control.

I have been banned from performing by security staff while everyone there who heard me perform formed a mob begging and demanding that I be allowed to entertain them and the security didnt care what their customers said.

I have even had the experience of security staff demanding that I pay a venue that I happened to be near, 1000 dollars (uk equivalent) for me to be given permission to play in the street outside that venue.

These people are either thieves bullies or mentally ill or all three, but we have to suffer them.

The only way forward is to approach the people in charge and get an agreement allowing us to perform.

In the case of a cruise the steward of the cabins would probably allow quiet practice if they could hear just how quiet we can be.

I am put in mind of a trumpet player who travelled to an islamic country where music was banned and the immigration staff wanted to confiscate his trumpet on entry, but when the player played for them to demonstrate just how quiet he played they quickly realised they were quite wrong and then allowed the player in with his instrument without any issues, they just asked him to be respectful.

People think instruments are always loud offensive and nasty sounding and can wake the dead and of course that just is not true.

Amateurs who have no control or skill and recent offensive playing of the Vuvuzella for example has made people fear us and that instrument from hell and they now fear all musicians because of it.

A local agreement with the people in charge locally can go a long way to resolving these kinds of issues.

I think we need to work with people and change attitudes where we can.

The one thing we must not do I believe is to hide and sneak instruments in and then be discovered breaking the rules.