Write Only Memory

I was going to post more about ATHF shutting down Boston - on the news when they kept explaining that the signs looked like bombs because they have batteries and wires my head almost exploded. I started making a list of every day items that have batteries and wires, but it quickly got far too long. I did find it hilarious that the news blurred out a series of LEDs that very roughly approximate an alien holding up its middle finger. (Ok I guess I ended up writing about it.)

But, then I read a paper in JSSC that discussed write only memory and I decided to write about it instead. When I was working in the LCS (laboratory for computer science at MIT - now part of CSAIL) there was an ad on the wall for write only memory. I'm pretty certain the ad was a joke (if you don't get it - try to think about how you would use memory that you can write to but cannot read from) (I guess it is a bit like /dev/null which is useful, but I digress...). Then, today I was reading a paper about an electric braille device. I was going to explain how the whole thing works, but the explanation was getting long. The point is that the device actually contains some write only memory! They are cheating a bit since the contents of the memory do go to the actuators that move the little braille bumps, but the memory does not have a read line and they were able to use 5 transistors per bit instead of the standard SRAM 6 transistors per bit.

For those who's eyes haven't glazed over yet - the reason they were working so hard to minimize transistor and interconnect count is they are using printable organic transistors. Of course it has a while before it becomes a product since the transistors degrade after a month (and that's when it is encased in nitrogen - in air it is even faster).