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by jahboater
Tue Dec 22, 2015 8:26 am
Forum: General discussion
Topic: Raspberry fan needed?
Replies: 10
Views: 1629

Re: Raspberry fan needed?

Do I really need fan for raspberry if I overclock raspberry? does it matter if I don't have The chip (SoC) is similar to those used in mobile phones - think of it placed in a tiny unventilated case and that case then put in someone’s pocket. The Pi is very robust and you will not damage it easily. ...
by jahboater
Mon Dec 21, 2015 5:46 pm
Forum: General discussion
Topic: catapult project ( raspberry pi ) - physics - need help
Replies: 98
Views: 11978

Re: catapult project ( raspberry pi ) - physics - need help

Commercial GPS update rate will be too slow I think (about a second per measurement?). It also has issues with heights and speeds over a certain altitude (to stop it being used for rocket guidance). But perhaps worthwhile adding for completeness. Yes indeed, once per second - I agree it sounds unsu...
by jahboater
Mon Dec 21, 2015 1:34 pm
Forum: General discussion
Topic: catapult project ( raspberry pi ) - physics - need help
Replies: 98
Views: 11978

Re: catapult project ( raspberry pi ) - physics - need help

The last GPS I had with a barometer would (by default) auto calibrate the barometric altitude from the GPS! It was sensitive to very small changes in height compared to the GPS though. Modern 60+ channel GPS sets receiving both GPS and Glonass, with differential corrections, are fine for altitude (f...
by jahboater
Wed Dec 16, 2015 10:30 am
Forum: Off topic discussion
Topic: Your first time coding experience
Replies: 38
Views: 5383

Re: Your first time coding experience

Fortran IV on punched cards.
Later came Z80 machine code in hex (in my spare time).
by jahboater
Wed Dec 16, 2015 10:15 am
Forum: Beginners
Topic: How to mount SD card in SanDisk ImageMate 8 in 1?
Replies: 8
Views: 1699

Re: How to mount SD card in SanDisk ImageMate 8 in 1?

Plug the card reader in and then type "dmesg" - you might then see the device name within the last few lines even if the mount failed.
by jahboater
Wed Dec 16, 2015 9:59 am
Forum: Beginners
Topic: installing an OS using Linux mint
Replies: 3
Views: 3066

Re: installing an OS using Linux mint

I use Linux Mint. In general, installing the OS is easier on Linux because the required software (a) works and (b) is included as standard. The latest Rasbian is rather large (over 4GB) and some versions of Windows unzip fail - needing "p7zip" to be installed. The Linux unzip has handled the new for...
by jahboater
Mon Dec 14, 2015 3:27 pm
Forum: General discussion
Topic: Minecraft for raspberry pi ?
Replies: 6
Views: 956

Re: Minecraft for raspberry pi ?

The Pi was 32-bit last time I checked ...
by jahboater
Mon Dec 14, 2015 9:08 am
Forum: C/C++
Topic: Recommended C IDE
Replies: 27
Views: 9020

Re: Recommended C IDE

There is also the simple IDE geany (sudo apt-get install geany). Or just use your favourite text editor (vi or nano perhaps), gcc, and gdb.
by jahboater
Sat Dec 05, 2015 9:28 am
Forum: Beginners
Topic: Pi Store Redirect to Paypal?
Replies: 7
Views: 1789

Re: Pi Store Redirect to Paypal?

Perhaps:

sudo apt-get install doomsday
by jahboater
Wed Dec 02, 2015 11:51 am
Forum: General discussion
Topic: Pi Zero device tree model name
Replies: 1
Views: 394

Pi Zero device tree model name

I noticed the name in device tree needs updating for the zero.
In /sys/firmware/devicetree/base/model

Pi2: Raspberry Pi 2 Model B Rev 1.1
B+: Raspberry Pi Model B Plus Rev 1.2
Pi0: Raspberry Pi ? Rev 1.2
by jahboater
Wed Dec 02, 2015 8:56 am
Forum: General discussion
Topic: Going Lower level, assembly & choosing hardware.
Replies: 22
Views: 3274

Re: Going Lower level, assembly & choosing hardware.

I did notice that nearly all the resources for assembly on Pi are for the original board... from what I understand there isn't a lot of difference between ARMv6 and v7 so I should be able to adapt what I read for my Pi2 using these forums and the ARM doco's. Yes, everything you learn on the armv6 w...
by jahboater
Tue Dec 01, 2015 8:29 am
Forum: General discussion
Topic: What if Raspberry Pi fails to boot?
Replies: 3
Views: 455

Re: What if Raspberry Pi fails to boot?

Or take the SD card out and put it in another Linux computer with a usb adapter. It should automount and you can edit /etc/rc.local in the ext4 / partition. Put it back in the Pi and reboot.
by jahboater
Mon Nov 30, 2015 5:20 pm
Forum: General discussion
Topic: Going Lower level, assembly & choosing hardware.
Replies: 22
Views: 3274

Re: Going Lower level, assembly & choosing hardware.

Don't forget the 8 bit stack pointer on the 6502 :lol:
by jahboater
Mon Nov 30, 2015 11:15 am
Forum: General discussion
Topic: Going Lower level, assembly & choosing hardware.
Replies: 22
Views: 3274

Re: Going Lower level, assembly & choosing hardware.

This book is quite useful for asm programming on the Pi:

http://www.amazon.co.uk/Raspberry-Assem ... _1?s=books
by jahboater
Mon Nov 30, 2015 9:03 am
Forum: General discussion
Topic: Going Lower level, assembly & choosing hardware.
Replies: 22
Views: 3274

Re: Going Lower level, assembly & choosing hardware.

Its perfectly easy to program in assembler directly on the Pi. Easier than installing another layer of software in between (an emulator) and much easier (IMHO) than using an old 8-bit instruction set such as the 6502 (especially the 6502). Yes, there are a lot more instructions and addressing modes,...
by jahboater
Fri Nov 27, 2015 9:16 am
Forum: General discussion
Topic: Raspbian Jessie Lite now available
Replies: 55
Views: 197003

Re: Raspbian Jessie Lite now available

No python3 which was a bit surprising.
Only an apt-get away though.
by jahboater
Thu Nov 26, 2015 9:07 pm
Forum: General discussion
Topic: Raspbian Jessie Lite now available
Replies: 55
Views: 197003

Re: Raspbian Jessie Lite now available

dpkg -l +++-==========================-==================-==================-========================================================= ii acl 2.2.52-2 armhf Access control list utilities ii adduser 3.113+nmu3 all add and remove users and groups ii alsa-utils 1.0.28-1 armhf Utilities for configuring...
by jahboater
Thu Nov 26, 2015 7:31 pm
Forum: General discussion
Topic: Raspbian Jessie Lite now available
Replies: 55
Views: 197003

Re: Raspbian Jessie Lite now available

-rw-r--r-- 1 jah jah 1458569216 Nov 21 21:32 2015-11-21-raspbian-jessie-lite.img
-rw-r--r-- 1 jah jah 392967934 Nov 26 19:21 2015-11-21-raspbian-jessie-lite.zip
2GB card should be fine.
by jahboater
Thu Nov 26, 2015 4:44 pm
Forum: General discussion
Topic: Benchmarking a raspberrypi compared to my own PC [obsolete and locked]
Replies: 51
Views: 18575

Re: Benchmarking a raspberrypi compared to my own PC

The superlinear speedup when moving from 1 to 2 cores is interesting. Do you notice this with the i7 builds as well? Even though there are only 4 cores, I wonder if the build time would continue to decrease with -j5 or -j6. No, with 16GB of memory it is never worth building with less than -j4 on th...
by jahboater
Wed Nov 25, 2015 5:19 pm
Forum: General discussion
Topic: Benchmarking a raspberrypi compared to my own PC [obsolete and locked]
Replies: 51
Views: 18575

Re: Benchmarking a raspberrypi compared to my own PC

The biggest build I ever did on the Pi2 was gcc 5.2 itself which took:- -j1 48 hours -j2 23 hours -j3 17 hours -j4 15 hours (takes about 2 hours or so on my 16GB core i7 with -j4). -j2 or more required additional swap space. I think there are a few very large source files in gcc. Especially with j3 ...
by jahboater
Wed Nov 25, 2015 1:56 pm
Forum: General discussion
Topic: Benchmarking a raspberrypi compared to my own PC [obsolete and locked]
Replies: 51
Views: 18575

Re: Benchmarking a raspberrypi compared to my own PC

And the Rpi2 is the size of a credit card, compared to the PC which is a medium sized tower! It goes fractionally faster on the Pi2 with -mthumb perhaps because more instructions fit in the I-cache. Using gcc 5.2 on the Pi2 did not help. That benchmark is very synthetic. I have just timed a real C c...
by jahboater
Wed Nov 25, 2015 8:29 am
Forum: General discussion
Topic: Benchmarking a raspberrypi compared to my own PC [obsolete and locked]
Replies: 51
Views: 18575

Re: Benchmarking a raspberrypi compared to my own PC

For the 900 MHz Pi2, I tried adding the usual compiler options to specify the exact CPU type and the results were dramatically improved (down from 27.7 to 7.2 secs) putting it closer the 2.8GHz Pentium 4. pi@pi2 ~ $ gcc -O3 -mcpu=cortex-a7 -mfpu=neon-vfpv4 prime.c -lm pi@pi2 ~ $ time ./a.out; time ....
by jahboater
Wed Nov 25, 2015 4:57 am
Forum: General discussion
Topic: Benchmarking a raspberrypi compared to my own PC [obsolete and locked]
Replies: 51
Views: 18575

Re: Benchmarking a raspberrypi compared to my own PC

For 900MHz Pi2, built with gcc 4.9.2:- pi@pi2 ~ $ time ./a.out; time ./a.out; time ./a.out Found a total of 664579 primes! real 0m27.697s user 0m27.690s sys 0m0.000s Found a total of 664579 primes! real 0m27.721s user 0m27.690s sys 0m0.020s Found a total of 664579 primes! real 0m27.722s user 0m27.70...
by jahboater
Tue Nov 24, 2015 11:00 pm
Forum: General discussion
Topic: Benchmarking a raspberrypi compared to my own PC [obsolete and locked]
Replies: 51
Views: 18575

Re: Benchmarking a raspberrypi compared to my own PC

On my Pi2 (at 900Mhz) the "benchmark" takes from 0.123 sec to 0.180 sec
Using the standard (on Jessie) gcc 4.9.2
by jahboater
Tue Nov 24, 2015 3:31 pm
Forum: General discussion
Topic: How to install Wheezy from Noobs
Replies: 12
Views: 2035

Re: How to install Wheezy from Noobs

Bottom line is that I can't imagine that systemd is the reason our opening poster, TheAuthor, want's to not use Jessie. So I'm curious as to his desire to hang on to wheezy. Agreed, I am sure 99.99% of Pi users have not noticed any difference with systemd (apart from the faster boot time). But perh...

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