2020 Newsletter: 24/34 — PreviousNext — (Attach.)

Sydney Harbour

Hello and Welcome,

“Web Design Group Zoom Meeting this Afternoon (16 May 2020)”:

Hi Everyone,

Our Web Design group will have a Zoom meeting on Saturday, 16 May 2020, at 2 pm.

Here are the details:

Sydney PCUserGroup is inviting you to a scheduled Zoom meeting.

Topic: Sydney PCUserGroup's Zoom Meeting

Time: 16 May 2020, 02:00 pm Canberra, Melbourne, Sydney

Join Zoom Meeting — Details to be sent by separate e-mail


Meeting ID: nnn nnnn nnnn nnnn

Password: pppppppppp

I am sorry for the late notice. I have been busy with insurance problems, so I haven't had much time to prepare for this month's meeting.

One of the topics on our list for this year is Pre-processors. You may have heard of SASS (Syntactically Awesome Stylesheets), LESS (Learner Style Sheets) and Stylus. These are programs that enhance and "simplify" writing CSS code.

They all appear to run in JavaScript, and you need to install Node.js to run them. We will have a look at how they work.

Have you ever run a trace-route or pinged your site? My cPanel keeps dropping out, and NetRegistry asked me to run these checks using the command line. So we will have a look at how to run these checks and what the results mean.

I will send a reminder with the links to the Zoom meeting at 1:30 pm on Saturday.

— Steve South

“Zoom News”:

Here's how to hide the column of participants' videos when someone is using "Share Screen":

Just one hour to upgrade Ubuntu versions
Hide video pictures from the screen.

Hover over the top of the column of videos to show the "title-bar", then click the single dash icon ( — ).

We will see a roll-up of all the pictures which leaves only a single (moveable) black-background bar with the current speaker's name on it.

Alternatively, we can reduce the size of the "Share Screen" by clicking on "View Options v" (See pic, below) and choosing "50%, 100% (default) or 200%" etc.

In this mode, you can use the mouse pointer (which is now a hand) to drag parts of the picture into or out of view for easier viewing.

This pic shows the 50% choice:

Just one hour to upgrade Ubuntu versions
Change screen-size, so all details are visible.

It looks like there are more Zoom adjustments available than we thought.

The time limit of 40 mins is back.

If you're using the Free version of Zoom, the time limit of 40 minutes is now strictly enforced. A timer countdown starts, on your screen, at about 10 minutes. When it expires, you get 60 seconds to say your quick "Goodbyes" before you are dumped unceremoniously back onto your Desktop.

— Ed.

Meeting This Week:

Tuesday Forum - Tuesday, 19 May - 9:30 am (10:00 am meeting start) - noon

We have cancelled this meeting until further notice.

Meeting Next Week:

Main Meeting - Tuesday, 26 May - 5:30 pm (6:00 pm meeting start) - 8:00 pm

We will be running this meeting using Zoom; details later by e-mail.

Current & Upcoming Meetings:

29 2020/05/02 — 14:00-17:00 — 02 May, Saturday — Penrith Group
30 2020/05/08 — 09:30-12:30 — 08 May, Friday — Friday Forum
31 2020/05/08 — 12:30-15:30 — 08 May, Friday — Communications
32 2020/05/12 — 17:30-20:30 — 12 May, Tuesday — Programming SIG
33 2020/05/16 — 13:30-16:30 — 16 May, Saturday — Web Design
34 2020/05/19 — 09:30-12:30 — 19 May, Tuesday — Tuesday Forum
35 2020/05/22 — 09:30-12:30 — 22 May, Friday — Digital Photography, [ Discontinued ]
36 2020/05/26 — 17:30-20:30 — 26 May, Tuesday — Main Meeting


Tech News:

“Chrome Opens Off-screen, Does not Retain its Position on Close”:

See the Askubuntu thread from 3 years, two months ago!

So, it's not a new problem. It also appears to affect Windows and Linux.

One of our Members has experienced this bizarre behaviour when using the Chrome browser.

There are also reports of it appearing in Microsoft's Edge.

The bug is probably buried deep in the Chromium codebase.

Suggestion 1:

Use the key combination ALT+TAB until you have selected Chrome before continuing with the next step.

Press ALT + Space: This opens the "Window Menu".

Choose "Move" either by clicking on the option if you can see the menu or by hitting the "M" key.

Hit one of the "arrow" keys, the one with a direction opposite to where your browser window has gone (mine went to the right, so I hit the "left arrow" key) enough times until you can see some of the browser to be able to drag it.

Drag the browser to the desired position.

Close the browser (this is important to ensure that this new position of the browser is saved and will be the position of the browser the next time you open it. Skipping this step means that the last saved position is "off-screen". Should the browser close improperly, it will re-open in the last saved position, that is "off-screen", and you will have to repeat the procedure.)

Re-open your browser and proceed normally.

Suggestion 2:

If you're doing it in Incognito Mode, moving or resizing the Chrome window to the desired location (and closing it to save the new position) will not work. You'll have to do it on the standard window for it to work.

Suggestion 3:

In my case, it was one of the Chrome extensions that was causing the problem. I turned off all the Chrome extensions, and then turned them on one at a time and opened Chrome until I found the culprit (in my case it was the "Max Payback" extension which somehow uses what is called OpenResty). Now Google Chrome works well (and I turn this extension on only when I need it and then turn it back off).

I hope this is useful/helpful!

Incredible — Ed.

“Know the NSW Road Rules”:

Referred by John Lucke:

I have attached a short article about knowing the current NSW road rules that may be of interest to Members.


With the COVID-19 travel restrictions gradually being eased and you're keen for a nice long drive, perhaps now's a good time to revise your road rule knowledge.

Several sites allow you to choose from multiple choice answers to questions in a range of NSW road rule topics. Try this example:

How close can you park to another vehicle when parked parallel to the kerb?

A. You must leave at least 1-metre front and back

B. You must leave at least 1.5 metres front and back

C. You must leave at least 2 metres from the front only

D. You must leave at least 3 metres front and back

We suggest using an Ad-Blocker since the best test sites are commercially sponsored.

Car driver knowledge tests: https://­www.easydrivingtest.com.au/­driving-test/­dkt/­car.

NSW RTA Test Practice 2020: https://­aussie-driver.com/­nsw/­nsw-dkt-practice-test-1/

Hint to correct answer: FEEDBACK @ 6

— John Lucke

“Why Did Dial-Up Modems Make So Much Noise?”:

See the How-To Geek article by BENJ EDWARDS | @benjedwards 9 MAY, 2020, 6:40 am EDT.

Screeeech . . . hisss . . . squaawk. These are familiar sounds to anyone who's ever used dial-up internet or called BBSes. It seemed especially noisy late at night. Have you ever wondered why all that noise was necessary? And did you know you could have muted your noisy modem?

Why the Screeches?

If you interrupt a modem connection by picking up a telephone handset and listening, you'll hear screeches, hissing, buzzing, and various other noises.

"That is the actual sound of the data being sent and received," said Dale Heatherington, a co-founder of Hayes Microcomputer Products and the circuit designer of the first direct-connect modem with a speaker.

In particular, the sounds you hear at the beginning of a modem connection are the two modems "handshaking." Handshaking is the process of two modems testing the waters, and negotiating settings, such as which speed and compression methods to use.

This detailed chart, created by programmer Oona Räisänen in 2012, breaks down all the sounds you hear during the handshaking process. [ The web-page lets you play the modem sounds — Ed. ]

But, wait a minute, why are we listening to modems perform this intimate dance in the first place?

Why Did Modems Even Have Speakers?

Before 1984, the U.S. telephone network was a monopoly controlled by AT&T. The firm had strict rules about who was allowed to connect a device to its network. The earliest dial-up modems used devices called acoustic couplers, which allowed modems to be acoustically, but not electronically, linked to the system.

To operate a modem with an acoustic coupler, you would pick up the phone, dial a number, and then listen for either a modem or person to answer on the other end. When all was clear, you set the receiver down in two cups that acted as a microphone and speaker. The connection would then begin.

After new FCC rules relaxed AT&T's restrictions in the mid-1970s, firms began to create direct-connect modems that hooked directly to the telephone system using modular plugs.

However, if a direct-connect modem dialled out and failed to establish a connection, there was no longer a telephone receiver at your ear to let you know what was wrong. A line could be busy or disconnected, an answering machine could pick up, or you could reach a fax machine instead.

To solve this problem, Hayes Microcomputer Products included an internal speaker in its breakthrough 1981 modem for personal computers, the Hayes Stack Smartmodem 300.

How Do You Turn Off the Screeches?

Not coincidentally, the first modem with a built-in speaker — the Smartmodem 300 — was also the first that allowed you to turn off that speaker. You did it with special codes called the Hayes Command Set. These command codes allowed people to change modem settings via simple commands with an AT prefix that you send through terminal software.

To turn off the speaker, you sent the serial command AT M0 before dialling. (Tuck it into your modem initialization string.) You could also control the volume of the speaker using commands like AT L1. Here's a page from the 1992 Hayes Modem Technical Reference that explains it all:

Did you know you could mute those old modems?
Using AT M0 will mute those old modems.

Read more »

“How Easy is it to Upgrade Linux Versions?”:

I just got a pop-up, the other day, offering to upgrade my Ubuntu 19.10 (Oct 2019) to 20.04 (Apr 2020), and they said it would only take about an hour.

Sure enough, it started at 1:33 pm and ended at 2:35 pm, with 1378 packages upgraded. Amazing.

There was only about 900 MB to download, but look at the simplicity of the Upgrade Menu:

Before: Ubuntu OS nickname — EOAN ERMINE

Just one hour to upgrade Ubuntu versions
Ubuntu 19.10

After: Ubuntu OS nickname — FOCAL FOSSA

Package count updated: 1378
Ubuntu 20.04

FOSSA? If it had black fur, it would look like a Panther.

“The Fossa (Cryptoprocta ferox) is the largest carnivorous mammal on the island of Madagascar. They can reach nearly six feet in length, with half of that due to their long tails. They look like a cross between a cat, a dog, and a mongoose”.

At least the eyes are drawn better than the blank Ermine-eyes, above!

— Ed.

“Microsoft is Fixing one of the Worst Things about E-mail”:

Referred by Jeff Garland: See the BGR (Boy Genius Report) article by Chris Smith @chris_writes 11 May 2020 at 6:50 am.

Microsoft has enabled a Reply-All Storm Protection feature to all Office 365 accounts worldwide.

The feature will prevent people from using the reply-all response to e-mail chains once the e-mails meet certain conditions.

The protection will kick in once ten people use "reply-all" to e-mails involving over 5,000 recipients within 60 minutes.

We may be talking to friends and coworkers via instant messaging more than ever, but e-mail isn't going away anytime soon. Like it or not, we all depend on e-mail to some extent, and we're yet to see anyone overhaul the e-mail experience. But several companies are still trying to improve e-mail, and one of them is trying to fix one of the worst things about e-mail. Microsoft has just enabled a feature it announced last year on Microsoft 365 (Office 365) accounts that will prevent annoying "Reply-All Storms" in the future.

If you've been at the receiving end of a "reply-all" e-mail chain, you know how bad things can get. Someone in your organization chose "reply-all" instead of "reply" intentionally or by mistake, and all hell broke loose from there, as others may have chosen to go for "reply-all" responses themselves.

Microsoft announced plans to enable a Reply-All Storm Protection feature on e-mail accounts at Ignite 2019, and it is finally ready to roll out to all Microsoft 365 accounts worldwide:

Initially, the Reply-All Storm Protection feature will mostly benefit large organizations who have large distribution lists. When the feature detects a likely reply-all storm taking place on a big DL (Download), it will block subsequent attempts to reply-all to the thread and will return an NDR (Non-Delivery Receipt) to the sender. The reply-all block will remain in place for several hours.

The Reply-All Storm Protection will work using the following conditions at first: "10 reply-all-s to over 5000 recipients within 60 minutes." Once a storm is detected, the replies will be blocked for four hours, offering the following message to anyone attempting to reply to the conversation:

The conversation is too busy, with too many people.

How to Fix It:

Don't resend the e-mail.

Send to a smaller number of recipients.

Those parameters might change in the future, Microsoft explained in its advisory, as the company will tweak the feature based on customer feedback and analytics.

While the feature is active on your Outlook account, you won't start noticing it until the next massive reply-all storm hits. Microsoft says the function is already working internally:

We already see the first version of the feature successfully reduce the impact of reply-all storms within Microsoft — humans still behave like humans no matter which company they work for ;) and believe it will benefit many other organizations as well.

The Reply-All Storm Protection feature is something other companies should consider adding to their e-mail products in the future.

Read more »

Fun Facts:

“Telescoping Series”:

Last week's puzzler:

Can you find the sum of the infinite series: 1/(1 · 6) + 1/(2 · 7) + 1/(3 · 8) + 1/(4 · 9) + … ?

Here, the typical term is 1/(n · (n+5)), or 1/5 · (1/n - 1/(n+5)), so do these terms "cancel out" after a while?

They do, but can you find the sum?

Adding 500,000,000 terms, we get the sum equal to:


But what is this number?

Hint 1: Multiply the above number by 300, and you'll see something interesting.

Hint 2: Write out the first dozen or so terms, using the "difference" format, and you'll see the pattern — a telescoping sum.


Hint 1: Let's multiply the above constant by 300:

That makes the number: 136.9999994000­0000359999­9973600000­2159999981­2032001699­1999842444­8009999999­999991…

Hint 2: Using the "difference" format for this sum, we get:

Sum = 1/5 · ( (1/1 - 1/6) + (1/2 - 1/7) + (1/3 - 1/8) + (1/4 - 1/9) + (1/5 - 1/10) + (1/6 - 1/11) + (1/7 - 1/12) + (1/8 - 1/13) + (1/9 - 1/14) ... )

Sum = 1/5 · ( 1/1 + 1/2 + 1/3 + 1/4 + 1/5 + ( - 1/6 + 1/6 ) + ( - 1/7 + 1/7 ) + ( - 1/8 + 1/8 ) + ( - 1/9 + 1/9 ) + ( - 1/10 + 1/10 ) ... )

The sum now consists of 1/5 · ( 1/1 + 1/2 + 1/3 + 1/4 + 1/5 ) + infinitely many terms like ( - 1/6 + 1/6 ), ( - 1/7 + 1/7 ) etc. which all cancel out in pairs.

Summing these terms, using the common denominator of 60, gives: 1/5 · ( 60/60 + 30/60 + 20/60 + 15/60 + 12/60) = 1/5 · ( 137/60 ) or: 137/300.

We thought so — Ed.

— The Collatz Conjecture —
“Mathematician Proves Huge Result
on 'Dangerous' Problem”:

See the Quanta Magazine article by Kevin Hartnett | Senior Writer | 11 December 2019.

Mathematicians regard the Collatz Conjecture as a dilemma and warn each other to stay away. But now Terence Tao has made more progress than anyone in decades.

Take a number, any number. If it's even, halve it. If it's odd, multiply by three and add 1. Repeat. Do all starting numbers lead to 1?

Experienced mathematicians warn up-and-comers to stay away from the Collatz Conjecture. It's a siren song; they say: Fall under its trance, and you may never do meaningful work again.

The Collatz Conjecture is quite possibly the simplest unsolved problem in mathematics — which is precisely what makes it so treacherously alluring.

"This is a dangerous problem. People become obsessed with it, and it is impossible to solve at the moment," said Jeffrey Lagarias, a mathematician at the University of Michigan and an expert on the Collatz Conjecture.

Earlier this year, one of the top mathematicians in the world dared to confront the problem — and came away with one of the most significant results on the Collatz Conjecture in decades.

On 8 September 2019, Terence Tao posted a proof showing that — at the very least — the Collatz Conjecture is "almost" true for "almost" all numbers. While Tao's result is not a full proof of the Conjecture, it is a significant advance on a problem that doesn't give up its secrets easily.

"I wasn't expecting to solve this problem completely," said Tao, a mathematician at the University of California, Los Angeles. "But what I did was more than I expected."

The Collatz Conundrum

Lothar Collatz likely posed the eponymous Conjecture in the 1930s. The problem sounds like a party trick. Pick a number, any number. If it's odd, multiply it by three and add 1. If it's even, divide it by 2. Now you have a new number. Apply the same rules to the new number. The Conjecture is about what happens as you keep repeating the process.

Intuition might suggest that the number you start with affects the final number. Maybe some numbers eventually spiral down to 1. Maybe others go marching off to infinity.

But Collatz predicted that's not the case. He conjectured that if you start with a positive whole number and run this process long enough, all starting values will lead to 1. And once you hit 1, the rules of the Collatz Conjecture confine you to a loop: 1, 4, 2, 1, 4, 2, 1, on and on forever.

An Unexpected Tip

But Tao doesn't entirely resist the great temptations of his field. Every year, he tries his luck for a day or two on one of math's famous unsolved problems. Over the years, he's made a few attempts at solving the Collatz Conjecture, to no avail.

Then this past August, an anonymous reader left a comment on Tao's blog. The commenter suggested trying to solve the Collatz Conjecture for "almost all" numbers, rather than trying to solve it completely.

"I didn't reply, but it did get me thinking about the problem again," Tao said.

And what he realized was that the Collatz Conjecture was similar, in a way, to the types of equations — called partial differential equations — that have featured in some of the most significant results of his career.

Inputs and Outputs

Partial differential equations, or PDEs, can be used to model many of the most fundamental physical processes in the universe, like the evolution of a fluid or the ripple of gravity through space-time. They arise in situations where the future position of a system — like the state of a pond five seconds after you've thrown a rock into it — depends on contributions from two or more factors, like the water's viscosity and velocity.

Complicated PDEs wouldn't seem to have much to do with a simple question about arithmetic like the Collatz Conjecture.


Tao's key insight was figuring out how to choose a sample of numbers that largely retains its original weights throughout the Collatz process.

For example, Tao weights his starting sample to contain no multiples of 3, since the Collatz process quickly weeds out multiples of 3 anyway. Some of the other weights Tao came up with are more complicated. He weights his starting sample toward numbers that have a remainder of 1 after being divided by 3. And away from numbers that have a remainder of 2 after being divided by 3.


Any proof of the full Conjecture would likely depend on a different approach. As a result, Tao's work is both a triumph and a warning to the Collatz curious: Just when you think you might have cornered the problem, it slips away.

"You can get as close as you want to the Collatz Conjecture, but it's still out of reach," Tao said.

Read more »

Bob Backstrom
~ Newsletter Editor ~

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