28 Jan
2006
28 Jan
'06
4:42 a.m.
At one point I had a lot of house-marked ceramic chip
packages
that I thought were DRAM but couldn't be certain of. Since they
were in cerdip packages, it was easy to use a cold chisel to
split one of them open. And I used a microscope to look at the
die, and sure enough, it was marked as a 4116 DRAM part. I used
the rest of the parts as 4116s. This would be MUCH more
difficult with plastic parts.
Ayone else remember the 'Optic RaM', a poor-man's image sensor.
From what I remember they were a normal DRAM chip with
a quartz lid to
the package (it's been suggested you could take a cerdip 4116
or 4164,
knock off the top and replkce it with a window).
The idea was you focussed an image onto the chip. Stored 1's in all
locations, waited a bit and read out the contents. Those cells which had
been exposed to enough light would read out as 0's. Do it again with
different waiting times (note, once you've read out a pattern, you've
lost the charge stored in the cells, you have to start again, you can't
read the chip repeatedly without filling it with 1's), combine the
resulting bit patterns to get a sort-of grey scale image.
Disadvantages were the fact you had to capture the same image several
times to get that grey scale, and the fact that there was an insensitive
strip down the middle of the die where the address logic, etc was.
-tony