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by jcyr
Thu Dec 05, 2019 10:16 pm
Forum: General discussion
Topic: Raspberry pi 4 power with out power adapter??
Replies: 6
Views: 304

Re: Raspberry pi 4 power with out power adapter??

I am assuming you are using a step down converter? Whatever the power source, you must deliver 5V (+/-0.25V) to the Pi. Depending on what is connected to it, a Pi4B may require up to 3A (15W). So some checks: Does the printer's PSU (at whatever voltage) have a spare 15W capacity? If the printer sup...
by jcyr
Thu Dec 05, 2019 5:30 pm
Forum: General discussion
Topic: Best audio solution for Pi 4 desktop config
Replies: 18
Views: 789

Re: Best audio solution for Pi 4 desktop config

Depends on sound quality you need. For audiophile quality, here's what I use:

PI3B+ with Hifiberry DAC Pro with analog power supply powering the audio section, Elekit TU-8200 Tube Amp, driving B&W DM 1400 speaker pair.
by jcyr
Thu Dec 05, 2019 5:06 pm
Forum: General programming discussion
Topic: Communication between windows OS program and Raspberry Pi Gpio
Replies: 2
Views: 95

Re: Communication between windows OS program and Raspberry Pi Gpio

Hello Everyone, I want to write a program using C ++ visual studio or Python (in Windows 10 ) where i want to access GPIO pins of raspberry pi(remotely) from the same program. Is that achievable ? if it is achievable then what kind of connection i have to make physically between pi and PC.(LAN,Wifi...
by jcyr
Thu Dec 05, 2019 1:17 am
Forum: General discussion
Topic: Raspberry Pi 4 is not a replacement for a real PC, (as it doesn't have Skype) sorry!
Replies: 72
Views: 2509

Re: Raspberry Pi 4 is not a replacement for a real PC, (as it doesn't have Skype) sorry!

Despite the endless Linux vs. Windows rhetoric, I find each has a place where advantages shine. For example, I rarely use the PI's desktop due to it's lack of applications I use daily on my Windows laptop, but rarely a day goes by I don't log in to half a dozen PIs of various vintages and a couple o...
by jcyr
Wed Dec 04, 2019 4:15 am
Forum: General discussion
Topic: Raspberry Pi 4 is not a replacement for a real PC, (as it doesn't have Skype) sorry!
Replies: 72
Views: 2509

Re: Raspberry Pi 4 is not a replacement for a real PC, (as it doesn't have Skype) sorry!

In hindsight would Eben have said "Desktop level of performance"? Would that have made a difference? Probably not! Not necessarily the case, but let's remember that Raspberry Pi (Trading) Ltd is a business and as for any business promoting its products one can expect a certain amount of marketing h...
by jcyr
Wed Dec 04, 2019 2:27 am
Forum: General discussion
Topic: Raspberry Pi 4 is not a replacement for a real PC, (as it doesn't have Skype) sorry!
Replies: 72
Views: 2509

Re: Raspberry Pi 4 is not a replacement for a real PC, (as it doesn't have Skype) sorry!

Removed the most trolling and nonsensical rant a poster (diogen151) made in this thread, it went into >/dev/null ;-) . Skype does not a PC make... and only a Microsoft lackey who drank the Microsoft kool aid would claim so, just to mask that there are other video messaging systems out there that ca...
by jcyr
Wed Dec 04, 2019 1:33 am
Forum: C/C++
Topic: Where can I begin learning C/C++?
Replies: 72
Views: 5767

Re: Where can I begin learning C/C++?

DarkElvenAngel wrote:
Tue Dec 03, 2019 11:14 pm
I agree wholeheartedly but schools always seem to favor these odd languages over something more useful.
I understand many institutions are turning to Python these days.
by jcyr
Tue Dec 03, 2019 5:59 am
Forum: General discussion
Topic: New Pi 4B v1.2?
Replies: 125
Views: 8418

Re: New Pi 4B v1.2?

So far as I can tell...that's backwards. The resistors are so that the PSU can sense what voltage and current levels to supply to the Pi. If the Pi is misidentified or can't be identified, a "smart" PSU/cable will supply the default of 5v at 900mA. No, the resistors are there to establish whether a...
by jcyr
Tue Dec 03, 2019 5:20 am
Forum: General discussion
Topic: Raspberry Pi 4 is not a replacement for a real PC, (as it doesn't have Skype) sorry!
Replies: 72
Views: 2509

Re: Raspberry Pi 4 is not a replacement for a real PC, (as it doesn't have Skype) sorry!

I suppose that by definition a desktop computer is one that satisfies your needs for what you do on the desktop! That of course will vary depending on the individual (and yes, plenty still use Skype!). Qualifying one as odd or obtuse says more about the source than the target, sounds defensive, and ...
by jcyr
Tue Dec 03, 2019 4:33 am
Forum: General programming discussion
Topic: Tatami Pi Fun.
Replies: 138
Views: 3862

Re: Tatami Pi Fun.

Any program that has been organized and carefully commented for literate clarity would likely lead to a greater understanding of what makes a suitable first programming language for beginners. Not sure I understand the point of translating the same few algorithms (which rely on the same underlying ...
by jcyr
Mon Dec 02, 2019 3:10 am
Forum: General programming discussion
Topic: Tatami Pi Fun.
Replies: 138
Views: 3862

Re: Tatami Pi Fun.

I now have a program from Fido which runs as $ OMP_STACKSIZE=4M time ./queue-openmp Pr(40000)=479909 T(63405342000)=1000 Lc=374 312.93user 0.05system 0:30.23elapsed 1035%CPU (0avgtext+0avgdata 151540maxresident)k 0inputs+0outputs (0major+37706minor)pagefaults 0swaps Spot would be very interested in...
by jcyr
Sun Dec 01, 2019 11:56 pm
Forum: General programming discussion
Topic: Tatami Pi Fun.
Replies: 138
Views: 3862

Re: Tatami Pi Fun.

Speaking of which. We have been living with C/C++ for so many decades we start to think it actually makes sense. Well no, it has made us crazy. Get this typical example: $ gcc -Wall -O3 -o prune prune.c prune.c: In function ‘doinit’: prune.c:16:14: warning: overflow in conversion from ‘long long in...
by jcyr
Sun Dec 01, 2019 10:07 pm
Forum: General programming discussion
Topic: Tatami Pi Fun.
Replies: 138
Views: 3862

Re: Tatami Pi Fun.

Everything is i64 in this code. Might be worth tweaking that... Most variable don't need to be 64 bits. As you've noticed for this particular case, 64 bit Pi is much better than 32 bit Pi. #include <iostream> const uint64_t smax = 100000000000ULL; const uint32_t Pnum = 40000; const uint32_t fnum = ...
by jcyr
Sun Dec 01, 2019 5:02 pm
Forum: General programming discussion
Topic: Tatami Pi Fun.
Replies: 138
Views: 3862

Re: Tatami Pi Fun.

Rust written OS only a few months away

https://www.theregister.co.uk/2019/11/2 ... lfhosting/
by jcyr
Sat Nov 30, 2019 12:22 am
Forum: General programming discussion
Topic: Tatami Pi Fun.
Replies: 138
Views: 3862

Re: Tatami Pi Fun.

Painting pictures with watercolors. My spouse is an accomplished artist. I keep telling her that there's far more intelligence applied to what she does than what I do. I can't begin to comprehend how she creates! How is it that you can use only blue, green, and orange to depict a human face that wi...
by jcyr
Fri Nov 29, 2019 9:19 pm
Forum: General programming discussion
Topic: Tatami Pi Fun.
Replies: 138
Views: 3862

Re: Tatami Pi Fun.

Having explored AI techniques, as far as I can tell there's much more A than I in it. Till AI can produce volume 4B of Knuth's I wont loose any sleep.
by jcyr
Fri Nov 29, 2019 6:11 pm
Forum: General programming discussion
Topic: Tatami Pi Fun.
Replies: 138
Views: 3862

Re: The Tatami-Free Rooms coding challenge.

For some reason only Knuth volumes 1 and 2 are sitting on my shelf, so more information about 7.1.4.215 would be appreciated. Maybe it is actually the exact question we've been focusing on. From volume 4A, problem 7.1.4.215 Find all domino coverings of a chessboard that are also tatami tilings. App...
by jcyr
Fri Nov 29, 2019 1:56 am
Forum: General programming discussion
Topic: Tatami Pi Fun.
Replies: 138
Views: 3862

Re: Tatami Pi Fun.

Because they are redundant syntax. Because they often contribute to cryptic, obfuscated code. Because there is no practical benefit. Performance wise or otherwise. I find: root += place << 1; simpler and easier to read than: root = root + (place << 1); Ok, here's the condensed version for 32 bit va...
by jcyr
Fri Nov 29, 2019 12:12 am
Forum: General programming discussion
Topic: Tatami Pi Fun.
Replies: 138
Views: 3862

Re: Tatami Pi Fun.

Heater wrote:
Thu Nov 28, 2019 11:40 pm
Performance wise or otherwise.
Redundant syntax! Performance or otherwise. :o

(distributive property)
by jcyr
Thu Nov 28, 2019 7:45 pm
Forum: General programming discussion
Topic: Tatami Pi Fun.
Replies: 138
Views: 3862

Re: The Tatami-Free Rooms coding challenge.

On a modern machine, including calls to sqrt may result in greater performance because the floating-point pipeline can run in parallel with the integer unit and this would also avoid the overshoot. Tatami carpets are still a thing!!! For those concerned with sqrt using emulated doubles on integer m...
by jcyr
Thu Nov 21, 2019 3:20 am
Forum: General programming discussion
Topic: Tatami Pi Fun.
Replies: 138
Views: 3862

Re: The Tatami-Free Rooms coding challenge.

To me, being a good programmer is knowing which algorithms to use for the job in hand, and also recognizing when a problem's small enough that you can brute-force it. Hmm... Being a good programmer is more than parroting other's creativity. In any case, I doubt I'll be participating much more in th...
by jcyr
Thu Nov 21, 2019 2:50 am
Forum: General programming discussion
Topic: Tatami Pi Fun.
Replies: 138
Views: 3862

Re: The Tatami-Free Rooms coding challenge.

In particular, the Woz would never call a person or any of the customers who purchase the computers that he engineered an idiot. Instead he simultaneously expresses a happy love of technology, people and life in general all at the same time. There are the Woz of the world, but then there are also t...
by jcyr
Wed Nov 20, 2019 2:58 pm
Forum: General discussion
Topic: Easily run 64-bit Debian Buster packages on a Raspbian system: new RPi4 / RPi3 image released (systemd-nspawn, LXDE)
Replies: 136
Views: 20580

Re: Easily run 64-bit Debian Buster packages on a Raspbian system: new RPi4 / RPi3 image released (systemd-nspawn, LXDE)

Makes perfect sense. However, be aware that some generic build scripts use uname to determine the native architecture, leading to building for arm64 which is not what you wanted in 32 bit mode. That's not the fault of this tool, that's just what happens when you run a 64bit kernel. Scripts that use...
by jcyr
Wed Nov 20, 2019 4:37 am
Forum: General discussion
Topic: Easily run 64-bit Debian Buster packages on a Raspbian system: new RPi4 / RPi3 image released (systemd-nspawn, LXDE)
Replies: 136
Views: 20580

Re: Easily run 64-bit Debian Buster packages on a Raspbian system: new RPi4 / RPi3 image released (systemd-nspawn, LXDE)

In 32 bit mode. On stock Raspbian. pi@raspberrypi:~ $ uname -a Linux raspberrypi 4.19.75-v7l+ #1270 SMP Tue Sep 24 18:51:41 BST 2019 armv7l GNU/Linux On Raspbian with npawn package installed. pi@raspberrypi:~ $ uname -a Linux raspberrypi 4.19.75-v8+ #1270 SMP PREEMPT Tue Sep 24 18:59:17 BST 2019 aar...
by jcyr
Tue Nov 19, 2019 3:37 pm
Forum: General programming discussion
Topic: git and merging branches
Replies: 8
Views: 550

Re: git and merging branches

Git branches are often used for maintaining releases. Development occurs on the HEAD branch and a new branch is created with each formal release. This makes it easy to back port bug fixes discovered in the head branch to previous release branches.

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