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by ejolson
Mon Feb 01, 2016 4:35 pm
Forum: General discussion
Topic: [BUG Report] Serious Pi password BUG!!! [Solved]
Replies: 32
Views: 4140

Re: Serious Pi password error!

I've checked there is no cap lock or anything wrong with the keys. I try this one out but to no luck.... At log in screen, Ctrl+Alt+F8 or Ctrl+Alt+F9 to get into shell prompt. But nothing happen, just a black screen with a blinking cursor. Cant even type anything. Now only Ctrl+Alt+Delete x2 to reb...
by ejolson
Mon Feb 01, 2016 5:44 am
Forum: General discussion
Topic: [BUG Report] Serious Pi password BUG!!! [Solved]
Replies: 32
Views: 4140

Re: Serious Pi password error!

A good habit to get into when changing passwords is try logging in with the new password before doing anything else. If you are in a GUI, leave it running and try starting a new session via ssh. Another thing to check is whether the caps lock is set and to take hands off the keyboard between typing...
by ejolson
Sun Jan 31, 2016 11:46 pm
Forum: Staffroom, classroom and projects
Topic: Learning about threads
Replies: 2
Views: 1168

Re: Learning about threads

I think you'll find that Linux does that. https://www.raspberrypi.org/forums/viewtopic.php?f=44&t=126643 The Google Go programming language was designed for threaded programming and has easy to use threading and synchronization primitives built in. It is available in the standard Raspbian distribut...
by ejolson
Sun Jan 31, 2016 9:38 pm
Forum: General discussion
Topic: [BUG Report] Serious Pi password BUG!!! [Solved]
Replies: 32
Views: 4140

Re: Serious Pi password error!

Device : Raspberry Pi 2 B, 32GB MicroSD, O.S 2015-11-21-raspbian-jessie 1- Install O.S 2- Expand MicroSD to full in raspi-config 3- Reboot Raspberry 4- Once reboot, goto raspi-config and change password to nofood4u2day 5- Reboot Raspberry 6- Now Log on as user name pi and password nofood4u2day scre...
by ejolson
Sun Jan 31, 2016 7:46 am
Forum: General discussion
Topic: Amstrad 1512 v Zero
Replies: 18
Views: 2208

Re: Amstrad 1512 v Zero

The PC was seriously crappy as a computer but building circuits to plug into that ISA/Intel bus was dead easy. I'm kind of curious that you a seeing speed ups of less than even 100 between an old 486 and a Pi. In the memory bandwidth tests I used 0.5MB for the 486DX-66 and 10MB for the Pi 2B. This ...
by ejolson
Sun Jan 31, 2016 5:22 am
Forum: C/C++
Topic: gcc5 repository
Replies: 10
Views: 5081

Re: gcc5 repository

As you increase towards -j4 it needs more and more memory, but never needs more than 1GB swap even with "make -j4" (at least it doesn't for me). That is interesting. I chose 2GB based on the rule of thumb that swap should be 2x available RAM. Getting by with less could be useful, especially for tho...
by ejolson
Sun Jan 31, 2016 12:29 am
Forum: General discussion
Topic: Amstrad 1512 v Zero
Replies: 18
Views: 2208

Re: Amstrad 1512 v Zero

If I remember this right, running a DOS test suite under dosbox on a model B gives a rating roughly equivalent to a 40Mhz 486, so blowing socks off should probably be uprated to blowing off socks, trousers, underwear and various other bits. Also, the 1512 was pretty much an IBM PC clone, so not ver...
by ejolson
Sat Jan 30, 2016 8:20 am
Forum: C/C++
Topic: gcc5 repository
Replies: 10
Views: 5081

Re: gcc5 repository

I use GCC 5.3 on the Pi2. I don't think you can get it from the repositories. You will have to build it yourself which takes a few hours! My recollection is a that few hours means about 8 when compiling on the Pi 2B. Note that you will need a 2 GB swap file for the compilation to finish. Though I h...
by ejolson
Sat Jan 30, 2016 6:12 am
Forum: General discussion
Topic: Amstrad 1512 v Zero
Replies: 18
Views: 2208

Re: Amstrad 1512 v Zero

Wikipedia gives the 11/780 1 Dhrystone MIPS at 5MHz. Interesting enough, the last entry in the table is...Raspberry Pi 2 with a value of 4744 D-MIPS at 1GHz. That value seems way too high for a single core and a bit on the low side for all four cores. Well...if you've got the Dhrystone test suite, ...
by ejolson
Wed Jan 27, 2016 7:36 pm
Forum: General discussion
Topic: VideoCore 4 GPU Driver Added to Linux Mainline in Kernel 4.4
Replies: 42
Views: 12529

Re: VideoCore 4 GPU Driver Added to Linux Mainline in Kernel

Cost of one engineer to do the VC4 OSS driver, $200k-$300k (multi year project) Cost to develop VC5 $20M. Numbers made up, but about the right sort of magnitude. $200k seems a bargain for what Eric Anholt is doing - if nothing else, Broadcom get a of of publicity. but if there will be no VC5 then v...
by ejolson
Wed Jan 27, 2016 3:44 am
Forum: General discussion
Topic: Unusual CPU Temperature
Replies: 13
Views: 1773

Re: Unusual CPU Temperature

In what timezone are you? As far as I know crontab uses UTC. I am in GMT+9. The unusual temperature increase happens at 6:05 AM UTC. There is about 12 hour difference (and 20munites more.) If it is networked, do you see unusual network activity at that time? Yes. I checked it after reading your com...
by ejolson
Tue Jan 26, 2016 7:17 am
Forum: General discussion
Topic: Why is ARM so cheap, and x86 so expensive?
Replies: 91
Views: 33920

Re: Why is ARM so cheap, and x86 so expensive?

Do what? What is an 86000? Maybe R61zt means the 68000? No...he probably means either the 8086 (or it's entry level "little brother", the 8088) or *possibly* the almost never used 80186. Note that he goes on to spew conspiracy theories about "286", which would be the 80286. The 68000 (with follow o...
by ejolson
Mon Jan 25, 2016 7:45 pm
Forum: General discussion
Topic: Why is ARM so cheap, and x86 so expensive?
Replies: 91
Views: 33920

Re: Why is ARM so cheap, and x86 so expensive?

I've recently been looking at small single-board computers that come with x86 processors, for a few reasons. One is I'd like a minimalistic computer that does everything my normal computer does (including running Windows-only software) except with cheaper running costs. I'd also like to run some ol...
by ejolson
Sun Jan 24, 2016 4:17 pm
Forum: General discussion
Topic: Obfuscation thread
Replies: 34
Views: 4540

Re: Obfuscation thread

I put thought and effort into my posts to this thread and find it discouraging that you have found it a pain to preserve the meaningful replies on the subject of code obfuscation and copy protection. The original post was serious and received reasonable advice that he and others including myself may...
by ejolson
Sat Jan 23, 2016 6:09 pm
Forum: C/C++
Topic: Creating Script to Log "top" Command Output
Replies: 8
Views: 1188

Re: Creating Script to Log "top" Command Output

You say you want a "script" yet you've posted this in the C/C++ forum. C and C++ are not scripting languages, they are compiled languages. Having seen how much memory and CPU some resource monitoring deamons written in interpreted languages use, it seems like a good idea to write a simple one in C ...
by ejolson
Thu Jan 21, 2016 10:24 pm
Forum: Off topic discussion
Topic: Minecraft for Education Coming Summer 2016 for $5/£3.50
Replies: 9
Views: 1686

Re: Minecraft for Education Coming Summer 2016 for $5/£3.50

So over a student's time in school, cheaper to buy a Pi2 with Minecraft, Python, and so much more. And you don't need a traditional PC. (I'll ignore the cost of peripherals, they are the same for Pis and for traditional PCs). Assuming a Pi will last 3 years and can be used by 5 students each year, ...
by ejolson
Thu Jan 21, 2016 7:09 am
Forum: General discussion
Topic: 2 node raspberry pi supercomputer
Replies: 71
Views: 13985

Re: 2 node raspberry pi supercomputer

<SNIP> but you may want to search the web for this. As you've continued this thread well beyond your original post, it seems likely you will eventually succeed in getting your Pi cluster to work. This will certainly require quite a bit of self study and searching on Google. So you knock me for sayi...
by ejolson
Thu Jan 21, 2016 6:51 am
Forum: General discussion
Topic: 2 node raspberry pi supercomputer
Replies: 71
Views: 13985

Re: 2 node raspberry pi supercomputer

LMGTFY Aha! Let me Google that for you to discover what LMGTFY means. Sometimes, people aren't certain what they need to learn in order to get started. This is why, for example, people go to school. Why university degrees have specific course requirements. And why it might be unwise to let a studen...
by ejolson
Thu Jan 21, 2016 1:58 am
Forum: Off topic discussion
Topic: Minecraft for Education Coming Summer 2016 for $5/£3.50
Replies: 9
Views: 1686

Re: Minecraft for Education Coming Summer 2016 for $5/£3.50

Microsoft has announced that it will be releasing an educational version of Minecraft during Summer 2016 for $5/£3.50 per student. It will emphasize building STEM and computing skills as well as blocky worlds, and licenses will work both on school computer systems and at home. I find it interesting...
by ejolson
Wed Jan 20, 2016 11:55 pm
Forum: General discussion
Topic: 2 node raspberry pi supercomputer
Replies: 71
Views: 13985

Re: 2 node raspberry pi supercomputer

Ben_is_best wrote:I tried

Code: Select all

sudo apt-get install openmpi
, but it said

Code: Select all

Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package openmpi
Any suggestions?
How about

Code: Select all

apt-get install openmpi-bin libopenmpi-dev
by ejolson
Mon Jan 18, 2016 8:35 pm
Forum: General discussion
Topic: 2 node raspberry pi supercomputer
Replies: 71
Views: 13985

Re: 2 node raspberry pi supercomputer

I've made the cluster, so now how do you combine the processing power to make a supercomputer? The standard API to harness the parallel processing power of a cluster for supercomputing applications is MPI. The package OpenMPI should be available in the Raspbian repositories. Except for speed, a clu...
by ejolson
Sun Jan 17, 2016 6:31 pm
Forum: Teaching and learning resources
Topic: Learning about linux(not shell)
Replies: 20
Views: 3913

Re: Learning about linux(not shell)

I thought maybe I should learn about the Linux itself, not like how to use it, but how it works, how i can alter it and etc... For example i learned about Linux kernel, drivers and sysfs from using my raspberry pi, but I want to know more, I googled and found nothing, mostly because i had no idea w...
by ejolson
Sun Jan 17, 2016 5:55 pm
Forum: General discussion
Topic: Good FTP server?
Replies: 10
Views: 49773

Re: Good FTP server?

Here are some copy tests; SSH - 3 Mbps Proftp - 6Mbps Vsftp - 7Mbps Pure-ftp - 8Mbps So yes, SSH is an option but a slow option, I would still rather go with ftp if its for internal use. The communications slowdown caused by encryption is related to the network speed versus the CPU speed. Any conne...
by ejolson
Fri Jan 15, 2016 5:29 pm
Forum: General discussion
Topic: 2 node raspberry pi supercomputer
Replies: 71
Views: 13985

Re: 2 node raspberry pi supercomputer

I am at a loss to understand, especially since the worst was ZERO to ZERO in "Gadget" Mode.... Zero to Zero communication must pass through the 2B. Specifically, every packet from the first Zero is sent to the 2B which then forwards it to the other Zero. Thus, it is not surprising that Zero to Zero...
by ejolson
Thu Jan 14, 2016 5:13 pm
Forum: General discussion
Topic: Ethernet/USB bottleneck
Replies: 23
Views: 6663

Re: Ethernet/USB bottleneck

Hi Guys, As per my previous post, Was wondering if anyone had tried a 5ghz 801.11ac Wi-Fi dongle, and seen if this provides more performance over USB than a LAN cable using a 100mbit connection? As WiFi is a broadcast medium where every connected device interferes with every other, putting the Pi o...

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