Develop Bugs

New MicroSD Card Question

Hey guy's I recently purchased a 8 GB MicroSD card and I got it in the mail today, so before putting it in my phone I put it on my computer and it doesn't read 8 GB it reads 7.59 GB. Why is this?

Capactities will never be exact. That is true of flash drives, hard drives etc. My iPod is theoretically 80GB but is actually only 76. Annoying...but that's just how it is

http://www.technical-assistance.co.uk/kb/hddsize.php
same thing really it's been the case for eons

sd cards
well they are true about how they always vary in capacity for posted size but for hardrives it usually actually is withing a couple percent, where as flash being very unstable memory can come with no memory lol, but also some of the memory is take up by foratting the device to work with operating systems and able to hold files and everything

That's because drive manufacturers measure like this:
1MB = 1000KB
1GB = 1000MB
And operating systems measure like this (the correct way):
1MB = 1024KB
1GB = 1024MB
So the card you bought has 8,000,000KB. The manufacturer claims that's 8GB. Windows sees it as...
8,000,000KB / 1024KB per MB /1024MB per GB = 7.629GB
Then a little bit of space is used for formatting, which leaves us with 7.59GB.

yeap!!
gtg465x said:
That's because drive manufacturers measure like this:
1MB = 1000KB
1GB = 1000MB
And operating systems measure like this (the correct way):
1MB = 1024KB
1GB = 1024MB
So the card you bought has 8,000,000KB. The manufacturer claims that's 8GB. Windows sees it as...
8,000,000KB / 1024KB per MB /1024MB per GB = 7.629GB
Then a little bit of space is used for formatting, which leaves us with 7.59GB.
Click to expand...
Click to collapse
Must of user needs to know how sizes arent exacts! just think about why it arent memoryes for 200MB over 256 or 32 not 30MB

[Q] need a little clarification

Hi guys, i am really confused. I purchased an epad off of ebay. i thought winning bid of $42 was worth it so i got it. after purchasing it i read throught the details. i liked it except for this one part where it says "TF card support 32GB extend max". It has 1 usb slot and 2 micro sd slots. Does it mean total per card it can support is up to 32 gb or 32gb all 3 combined :/ if anyone can answer this question id appreciate it. THank you.

What kind of tablet? and epad?

yes, its an epad. i havnt got it yet but i was gonna order a few cards for it too then so i needed to know
EDIT: ITS THE SAME EXACT THING AS THE LINK BELOW
http://cgi.ebay.com/TABLET-PC-10-2-...US_Tablets&hash=item3f078105c9#ht_6594wt_1139

Here is your answer
The ram is 256 mb
The sd card support is 32 gigs per slot.
If you can root the device you will make it run better but trying to put froyo with only 256mb ram might be an issue
Good luck.............. good price though
Note:
1. All Memory cards we selling are with the tablet pc and at cost price,we are sure them all be tested before shipment ,we do not accept returns,replacement or refund of the cards,thanks for your cooperation.
2. Not all games and software can be supported by G-Sensor (Depending on software compatible)
3. Device usually show storage at about 0.7-1.3GB, This is because we have pre-installed the android system and other software,this will occupy some memory.)
Processor: Infortm X220 1Ghz
Operating System: Google Android 2.1
RAM: 256MB DDR2
ROM: 2GB (Upgradable to 8-32GB)
External Memory: Supports up to 32GB TF Cards
Display: 1024×600 Resolution, 10”LCD Screen
G-sensor: 3 sides G-sensor
GPS: Built-in GPS (Not pre-installed maps)
CPU Infortm X220 1GHz ARM11
Operating System: Google Android 2.1
Memory: 256MB
Display Display: 1024x600 Resolution, 10”LCD Screen
Storage: 2GB
Direction sensor: automatically rotating the display screen
Net connect: RJ45 ENTER NET:10/100M
WIFI WIRELESS NET:802.11 b/g
USB 3G NET
Language Multi-Language
Web browsing: Google chome-lite Browser UCWEB Browser
Android Market: Suppot
E-mail: Mainstream web mail service gmail / yahoo mail / hotmail / sina mail/163 mail
Communication Software: YOUTUBE,FACEBOOK,IREAD etc.
Battery 9V 3000 HMA
HDMI: 1080P
GPS
Built-in GPS Not pre-installed maps
Camera: Built-in 1.3MP
socket/jack 2PCS TF SOCKET
2PCS USB-Host SUPPORT 3G,KEY BOARD,MOUSE ,USB FLASH DISK
AUDIO JACK, HANDSET JACK
1pcs HDMISOCKET
1pcs RJ45
1pcs power socket
Weather: Desktop Gadgets, support custom size (large, medium optional), support the replacement of the skin
Color Silver
Explorer: Android task killer / Andexploret
weight 705g
Package Including:
1 x 10" x220 Tablet PC
1 x GPS antenna
1 x Stylus
1 x Charger
1 x User Manual
1 x Earphone

Most Chinese tablets support 32 Gb per card but I don't know if I would bank on that. Wait and see if what you bought is worth it before you buy the cards lol

NFC Tags Compatibility

Some NFC tag are not compatible with any devices. Is there a specific model number on NFC that we need in order for it to work on Nexus 5?
Thank you.

palabook said:
Some NFC tag are not compatible with any devices. Is there a specific model number on NFC that we need in order for it to work on Nexus 5?
Thank you.
Click to expand...
Click to collapse
Complatible with ultralight and NTAG 203, the classic 1k not compatible with newer devices

Basically, stay away from Mifare Classic Tags - those are cheap and have tons of memory but are only compatible with specific devices.
You want to get tags that are NFC Forum Type 1 or Type 2 as they will compatible with ALL NFC devices.
As someone already mentioned NTAG203 Tags are the most affordable and readily available, but they do only have 137 bytes of usable memory - this will be plenty for most task launching applications, but if you want to create a full Vcard or if you use an NFC app that needs more memory then the Topaz 512 Tags are the next step up as they have about 450 bytes of usable memory are also universally compatible with all NFC devices.

I've been using nearWAVE tags without any issue.

Ultralight
hollywoodfrodo said:
Basically, stay away from Mifare Classic Tags - those are cheap and have tons of memory but are only compatible with specific devices.
You want to get tags that are NFC Forum Type 1 or Type 2 as they will compatible with ALL NFC devices.
As someone already mentioned NTAG203 Tags are the most affordable and readily available, but they do only have 137 bytes of usable memory - this will be plenty for most task launching applications, but if you want to create a full Vcard or if you use an NFC app that needs more memory then the Topaz 512 Tags are the next step up as they have about 450 bytes of usable memory are also universally compatible with all NFC devices.
Click to expand...
Click to collapse
Any idea if Ultralight tags will work with the Nexus 4/5/7?

aalaap said:
Any idea if Ultralight tags will work with the Nexus 4/5/7?
Click to expand...
Click to collapse
Ultralight tags should work without a problem. They are either Type 1 or Type 2 tags. Also newer tags - NTAG213, NTAG215, NTAG216 will work and the 216 variant has high memory...if you can find them for sale.

hollywoodfrodo said:
Ultralight tags should work without a problem. They are either Type 1 or Type 2 tags. Also newer tags - NTAG213, NTAG215, NTAG216 will work and the 216 variant has high memory...if you can find them for sale.
Click to expand...
Click to collapse
Yeah, I just read "stay away from Mifare" and then I realised that I just bought a 10-pack Ultralights that are also MIFARE, so I was a bit worried. But then I read elsewhere that NXP's MIFARE Ultralight (incl. Ultralight C) tags are NFC Forum Tag 2 type, so they're probably supported.
I need very minimal info to be stored for my application, so the 48-byte Ultralight should work just fine.
Update: I received the ordered tags and they work perfectly fine with the Nexus 5!

Anybody know which chips are used in the Jakcom R3F/R3 smart rings?

Hi there,
The R3 ring contains three chips, two of which are stated as "NXP Smart CDX" (Dual core NXP MCU chipset), it can emulate both 13.56 mhz and 125 khz chips. (One of the instruction pages says these are 2 different chips as well, it is not very clear) It may be a 13.56 mhz chipset emulating mifare and the like, and a 125 khz chip.
The "NFC chip" is stated as one of the NXP NTAG 21x's. I just don't know which one it is.
The R3F ring contains 2 chips, both stated as "High speed smart NFC Dual-core chips". All of the NFC chips claim 106 KB/s transfer speed which leads me to believe these ones are 21x's as well.
Does anyone have anything more specific on any of the chips? I have contacted the manufacturer, and received no response. I hear that is normal for them.
I don't want to link directly to the products as I may be accused of advertising. The jakcom website is easy enough to find.
I am hoping the "smart" chip, is a smart MX and can be used to emulate a type 4 card and run the JCOP OpenPGP applet.
Thanks for any info you can offer.

Did you ever buy a ring & find out what it's capable of?

This is what I got when I scanned mine:
NXP MIFARE Ultralight (Ultralight C) - NTAG213

Bump ?
So the R3 has both frequencies and R3f has 2 chips but same frequency?
Any new info you guys found?

I scanned mine with my phone (R3)
=============================
M1 - 13.56 MHz
ISO 14443-3 type A
(Mifare classic)
=============================
NFC - 13.56 MHz
ISO 14443-3 type A
ISO 14443-2 type A
(Mifare Ultralight)
=============================
ID - 125 KHz (found by researching the interwebz)
HID standard
Once I get an HID reader I'll update what I learn about the ID chip, based on the R3 I think it's safe to assume the two chips in the R3F are the same.

1. NXP MIFARE Classic EV1 (MF1S50), NfcA, 1KB, 16 sectors of 4 blocks each, 64 blocks of 16 bytes each, max transceive length 253 bytes, ATQA 0x0400, SAK 0x08
2. NXP NTAG213 (NT2H1311G0UDx, 50pF), NfcA, MifareUltralight, NDEF Type 2, maximum NDEF data size 144 octets (36 pages, 4 bytes per page), maximum message size 142 octets, max transceive length 253 bytes, ATQA 0x4400, SAK 0x00
No idea about the ID chip except it's 125kHz and it can be used to copy to it one of various access cards.
Note that because of the small antenna sizes some devices won't be capable of reading it even in direct contact.

[Q] Optimal RAID scheme for ROM source

Hi all,
Late last year I came into possession (dumpster dive find) of an HP ProLiant rackmount server. It started out with lackluster specs (single Xeon E5205, 2GB RAM, no storage, dead SmartArray/RAID battery), that I eventually upgraded the internals:
Dual Xeon X5270 (did not determine if the particular board supports quad-core/socket CPU's, played it safe with best-available dual-core CPU's instead)
32 GB fully-buffered DDR2 RAM (was my first upgrade via a subsequent dumpster dive)
250GB Mushkin SATA SSD
320GB Seagate 2.5" SATA HDD
Replacement SmartArray battery
With that I could complete an Oreo 8.0 build from clean in 55 minutes - my 3rd-gen i5 PC would do so in 40 - in spite of the Xeons calculating prime numbers faster then my i5, the server has twice the age in terms of I/O.
What I determined to be a significant barrier is the SATA-1 bus (that's right, the 1.5Gbps variety). SATA-1 has a theoretical maximum throughput of 187 MBps, but in real world, my SSD was still falling 50 MBps short in tests (and is not much faster than the HDD in this scenario for that matter):
Code:
[email protected] ~> sudo hdparm -tT /dev/sda
/dev/sda:
Timing cached reads: 15532 MB in 1.99 seconds = 7788.53 MB/sec
Timing buffered disk reads: 412 MB in 3.01 seconds = 137.06 MB/sec
[email protected] ~> sudo hdparm -tT /dev/sdb
/dev/sdb:
Timing cached reads: 16086 MB in 1.99 seconds = 8066.75 MB/sec
Timing buffered disk reads: 322 MB in 3.00 seconds = 107.30 MB/sec
[email protected] ~>
The SmartArray, however has and encourages SAS-1 (3 Gbps/375 MBps theoretical throughput). Since I decided I will be keeping the rack-mount for the long haul, I invested in a few SAS drives (4x 300GB, 10K RPM).
Question time.
While the SAS disks deliver, I wonder what RAID configuration would make the most sense. I was thinking RAID 10 all four (effectively oversaturating the SmartArray E200 at up to 440MBps unless there are two channels to split the load) for 600GB, or to RAID 5 three of the drives for 150-to-220 MBps throughput and have a spare - also making 600GB.
Then it was suggested to me to RAID 5 all four (if a drive fails, just means slower performance while running in that state and will be fine as long as a second does not fail - if I use the server at all in the meantime) for 225-to-330 MBps throughput and 900GB space.
Since the arrays' purpose is to provide a place for source code (lots of reads, including random ones, few writes during system load) as I will still use the SSD for ccache and out (a bit more about that later), which scheme would make the most sense? I am inclined to do the RAID 5 with all four drives now, even though I may need to do so with software (ZFS-on-Linux) since the E200 model can have the RAID 5 option turned off based on the cache size available (I should be fine though, luckily) or want to because the server is a WOL/on-demand machine so the cache battery protection is often drained/recharging for the first 50 minutes of boot anyway (I suppose the way around that for 90% of cases is to change the BIOS setting to power back on if power lost while operational if not already).
225-to-330 MBps throughput may be a reasonable enough improvement or hard to improve upon in the situation anyway, unless there is other important information in play. What do you think?
And if I ever get a hold of a spare SSD, I plan for a PCIe X4 SATA-3 riser to hook it up with. I would have got one by now, but it is doubtful they are bootable with this machine. All this and you may be wondering, why prop up a 10+ year old server? At the moment I have quotes prepared to replace my i5, and the current cost to do it the way I want is quite a bit more (ten-fold at least) than the $120 here, $50 there that I am doing with the server.
Many thanks.

Pinging @rwilco12 and @garwynn

A bit of an update:
Some significant details changed as well, but I have received the four drives and I used the SmartArray to create a RAID5 with all four (no spare), making a logical drive of 838 GiB. Transferred my 320 GB contents over (after making larger swap, /var and /home partitions) offline with a CloneZilla CD, rewrote the related UUID's in fstab and initramfs.
The new benchmarks (keep in mind I am currently downloading AOSP as well):
Code:
[email protected] ~> sudo hdparm -tT /dev/sdb
/dev/sdb:
Timing cached reads: 11008 MB in 2.00 seconds = 5515.37 MB/sec
Timing buffered disk reads: 1260 MB in 3.00 seconds = 419.86 MB/sec
[email protected] ~>
Because of the significant changes, there is a benefit to the SSD also:
Code:
[email protected] ~> sudo hdparm -tT /dev/sda
/dev/sda:
Timing cached reads: 11498 MB in 2.00 seconds = 5758.57 MB/sec
Timing buffered disk reads: 784 MB in 3.00 seconds = 261.23 MB/sec
[email protected] ~>
And where it is important, for a 70,296-object Android 8.1 build:
Code:
Package size: 327M
════════════════════════════════════════════════════════════════════════════════
#### build completed successfully (33:32 (mm:ss)) ####
[email protected]:~/carbon$
Because this is still a ProLiant server, I have been playing with the iLO interface - neat things in there.
Wait, did I say "still"?
Yeah, I found an unexpectedly good deal on a DL380 G6 (loaded with G7-era CPU's) that I was compelled to snatch up.