SanDisk has announced a postage stamp-sized flash iSSD product for tablet computers at the Flash Memory Summit, with capacity ranging from 4GB to 64GB. IDC has conveniently defined a new flash product category, embedded flash, for what are called "highly portable consumer electronics devices", presumably meaning anything from …
Is that the modern measure of SSD size now is it? How very 19th century!
Besides, Stamp-sized chips are quite big. Micro SD cards kick their ass capacity/size wise and they aren't even that clever.
Seems an incredibly non-story to me. I think sandisk feel a bit left out of the loop.
So basically you have a 4GB+ SATA drive on the motherboard
Which is ideal for "instant on" computers that have SATA interfaces - such as the laptops suggested in the article. It does sound rather heavyweight for simpe things like mobile phones, but maybe when they evolve into computing devices, with user writable and upgradable disk type operating systems, they'll see the benefit, too. This should help.
Gotta say, if I was in the market for a MB and I saw one with a built in SATA drive, I'd go for it.
The ratio of the total amount written to the capacity is 625:1. For many purposes that will be fine, provided that the wear levelling works. I would suspect that it will see out the lifetime of most notebooks on moderate usage. Fitted with a 128GB drive, this implies a lifetime write allowance of 80TB. If the notebook lasts 5 years, then that's 44GB per day used 365 days per year. Of course many notebooks won't be used that frequently or consistently,.
However, it the 625:1 the full story here? Flash memory is written out in large pages and a relatively small 4KB write can involve the controller writing out a very large page - maybe 128KB or more, depending on the page size of the memory. Controller optimisation with write caches and so on can reduce that overhead by "rolling up" writes into a few, larger ones. However, the issue here is does the 625:1 ratio apply at the back end (what the controller writes to cache) or the front end (what the computer writes to the drive)? If your "write allowance" is rapidly used up by many small writes (quite a common thing when managing file systems), then the drives might fail rather faster than the specifications would indicate.
What on earth does it need 157 pins for?
Sata needs 4, and there will be another 2 for power. The only reason for the remaining 151 I can think of is mechanical mounting - and preventing hobbyists unsoldering the 4G part out of a cheap music player and substituting a 16G one :-)
157 pins, indeed.
157 pins does seem rather a lot. Perhaps the little BGA package doesn't connect to the outside world via SATA. Probably there's a connected supporting chip which is the SATA interface.
Yeah, 157 and for good reason.
The 157 pins are there for a reason. In an "End-User" scenario you would find most pins either connect to the power planes for improved power distribution inside the chip, or are non-connect (NC).
Now with only Power and SATA signals documented, you will probably find a lot of the NC pads are actually connected to stuff like JTAG for the initial programming of the SATA controller's firmware, Direct access to the flash array's address and data lines for factory testing of the array, and any number of other functions.
One way to tell if such hidden functions exist is if some pads need to be pulled high or low for no other reason than the datasheet says it's required for proper operation but with no other reason.