Wednesday, September 7, 2011
FIRST: CPU and GPU always go together because they are on the same chip (i think) for mobile devices.
Here is what I consider the bare minimum for a tablet:
CPU: Cortex A8 or Cortex A9 - DO NOT buy an ARM 11 device.
Some popular cortex A8 CPUs in order of worst to best... (chips in green = best bang for your buck in my opinion)
Freescale IMX515 - Bottom Line Cortex A8 but widely used. Decent all around performance but particularly weak GPU
Telechips TCC8803 - Excellent Media Playback performance. I haven't seen much support for these on the forums though. Somewhat weak GPU (Mali 200). Probably a better choice than the IMX515 though.
TI OMAP 3530 - I am not particularly familiar with Texas Instrument mobile processors. I do know that this one carries a PowerVR SGX-530 which is a step up from the Mali-200 in terms of performance. These are used in a lot of Witstech Tablets
Samsung S5PV210 - A "cheap" variant of the processor used in the Samsung Galaxy Tab 7". It has a VERY STRONG GPU - SGX540 and excels at gameplay. However, due to the higher power draw of this variation of the chip, battery life tends to be a bit shorter for many devices. Overall battery life though is heavily dependent upon the size of the battery in the device as well, so your best bet is to read reviews of the specific device you are considering. The Herotab C8 is probably the most popular ChinaTab that has featured this chipset.
Samsung S5PV110 - This is the same processor as found in the Galaxy Tab 7". It carries the same SGX540 gpu as the 210 BUT it is a much more energy efficient processor. It tends to be more expensive than the S5PV210 but battery life and heat should be improved.
Rockchip RK2918 - This is a "brand new" Cortex A8 chipset recently released by Rockchip. DO NOT CONFUSE this with the RK2808 which is a much slower, much older ARM11 part. This chipset probably trades blows for the top spot with the S5PV210/110 chipsets. It has a Vivante GC800 GPU which, on paper, is significantly faster than the SGX540. It absolutely excels at media playback as it can do 1080p flawlessly. Being newer, power consumption seems to be "up in the air." Some chips seem to be more energy efficient and run at 3.7 volts while others seem to by power hungry and run at 7.4 volts. Read reviews, milage will vary from device to device. There are several 8" and 7" models out that feature this chipset.
--Some popular Cortex A9 CPUs in order of worst to best... (chips in green = best bang for your buck in my opinion)
NEC Renesas EV2 - Dual-Core Processor - Extremely energy efficient with the best battery life of all the chipsets (Cortex A8 and A9). Battery life is phenomenal on these. It provides snappy performance for pretty much all android functions (especially multi-tasking between multiple apps). It has a Samsung SGX530 GPU so 3D performance is "okay" but FAR from stellar. Unfortunately, this chipset has had a tumutuous time with firmware and Media Playback is not very good. Ongoing bugs are Youtube HD playback and Hi-Def 1080p video playback. The RENA3 is one a few devices that actually use this chipset, with a couple more devices coming out in the next few months. Currently, it is stuck at Android 2.2, however 2.3 has been promised.
AMlogic 8726M Cortex A9 - Single Core - An interesting chipset all around. It packs a PUNCH for a GPU. It features a Mali-400 powerhouse. The same GPU featured in the Samsung Exynos 4210 chipset. Unfortunatley, I am not very familiar with the actual performance of devices that use the AMlogic chipset though so I can't verify whether that GPU is really being "flexed" so to speak. I do know that poor battery life has been a gnawing issue for many devices built around the AMlogic chipset. Hopefully better firmware will lead this to being a phenomenal choice all around.
Tegra II 250 - Harmony - A cheaper, earlier variant of the Tegra II 250, found in lower-cost Tegra II devices. The Nvidia Tegra II is a VERY STRONG performer all around. It is a Dual Core Cortex A9 part. The older Harmony variant is "stuck" at Android 2.2 however.
Tegra II 250 - Ventana - Identical to the "harmony" version (I think) except that this is a newer design and it is found in all the expensive tablets that advertise the Tegra II. It is running Android 3.0 and up without issue.
MEMORY: AT LEAST 512 MB DDR2/3 - Don't settle for less... The only chipsets (from the list above) that I have seen paired with less memory are the TI OMAP and IMX515 chips.
TOUCHSCREEN: Capacitive Multi-Touch... NEVER RESISTIVE - People might argue with me on this one, but I have used high-quality resistive touch devices... the experience DOES NOT COMPARE to a good Capacitive multi-touch device. It is worth the money. Don't skimp . If you are trying to choose though, do realize capacitive is "far superior" technology at present.
BATTERY LIFE: Do some research... DO NOT GET A DEVICE with less than 5-Hours of stated battery life. As a general rule, if the processor says it is a 3.7 volt then it is probably going to get better battery life than another device that has a processor that is running at 7.4 volts with the same size battery (measured in mAh... ex. 3400 mAh). Cortex-A9 is also supposed to be more "energy efficient" than Cortex A8. These are extremely general guidelines though as battery life is affected by so many variables. Research the specific device model you are considering. Search Google, and the forums, and read, read, read . This is a bit of a "hill that I die on" so realize that I speak with some bias as it is an important issue to me personally.
ANDROID: Only get a device that ships with Android 2.2 (or later) from the factory. Just a decent rule of thumb.
FEATURES Just a list of "suggested items" that are nice to have but not vital...
1. WiFi-N - Almost all tablets support at least WiFi-G, but a growing handful support WiFi-N and the extra speed and connectivity is a good thing. This is also another "personal hill" for me though as I run a pure-N network at home (and am too cheap to buy another router to setup a "G" network also... lol). So, all my tablets have to at least support "N" connectivity.
2. Blutooth - I don't have much use for it... but you might! Keep an eye out for it as extra connectivity is never a bad thing.
3. GPS - Several devices have this, many don't. It just depends. It is definitely a nice feature to have though and I consider it a significant "bonus" for any device.
4. 3G - Expect to pay anywhere from $30 to $120 more for the same device if it comes equipped with built-in 3G (a sim-card slot). This allows you to put your cell phone carriers sim-card into the tablet and get 3G data connectivity, just like many smart-phones. This is an awesome feature but it can lower battery life. However, it makes your tablet extremely more usable as you are no longer tied to wiFi hotspots for internet.
5. HDMI-out - when it works, it is very cool feature. I have tested many tablets where they have an HDMI-out port, BUT, the firmware is buggy and it doesn't work. Anyhow, being able to connect up to your big screen and using your mobile tablet for some netflix is kind of cool.
6. USB Host port - Okay, this is two-fold. Pretty much all china-tabs support USB host, don't get a tablet that doesn't (USB host allows you to plug in usb devices like thumb-drives and keyboards and mice, just like you do on your pc, and use them with your tablet). Now, something that is really handy. MOST tablets have "mini USB" ports and you have to use an adapter to use USB devices with the host port. Some tablets however have a "full-size" USB host port. This is VERY HANDY.
7. USB charging - Pretty much all tablets come with a power-brick and that is the primary and often only way to charge them. Some tablets, however, support being charged via their mini-USB port. I have found this to be an EXTREMELY useful feature, especially for travelling. Many commercial GPS units and many Smart Phones use the same connection for charging. The voltage is always the same. Also, your computer can be used to charge your device. So, what this means is that if you own a newer Garmin, then you have a car charger for your tablet. If you have a smart-phone with the same adapter, then you have extra wall-chargers for your tablet. This is often a slower way to charge your device, but it is an excellent feature to have as you don't have to always lug your power-block around with you.
Here are just some thoughts on "screen size and resolution" as there are several and much of it is up to individual preference as to what is "best."
Suffice to say, you probably don't want to get anything smaller than a 7" device. I actually prefer the 7" widescreen form-factor for its weight, one-handed operation, and portability, but your desires may vary. Other common sizes/aspect ratios are 8" 4:3, 9.7" 4:3 10" Wide, and 10.1" Wide...
Screen Resolution has to do with how man pixels are crammed into that 7" or 8" or 9" screen. The higher the resolution between "same size screens" the better. 800x480 is the lowest and most common resolution. 1024x600 is the next and highest resolution for 7" devices though only a handful have it. 800x600 and then 1024x768 for 8" devices (which are often a 4:3 aspect ratio). 1024x600 and 1024x768/800 depending on aspect ratio for larger devices.
Higher-Resolution does look much nicer but it also tends to cost significantly more depending on the device. Just realize that a higher-resolution is a good thing.
Okay - I hope that covers all the major bases so to speak and really helps some folks make a decision. This should help you "eliminate" a LOT of choices. Then you can come on here and ask about specific models rather than just asking -generally- "what should I buy?" . I wish I had found an article like this when I first was shopping around, it would have saved me a lot of time. I hope it does the same for you!
P.S. - I operate TopNotchTablets and currently sell two 7" models. One is based off of the NEC EV2 platofrom and the other off of the RK2918 platform. Both meet the "minimum specs" above and also offer a lot of cool features. Neither offer built-in 3G though.