DRAM Imager ( was: EPROM erase times and lifespan )

Dave Dunfield dave09 at dunfield.com
Mon Feb 2 09:55:54 CST 2009


> Dave,
> 
> The Cyclops you mentioned below ( from 1975 ) used a MOSTEK 4008 with an
> Optical window. There is a guy still selling them for a " mere " $35 if you
> are so inclined.
> 
> You cannot just use a standard 64K DRAM chip for an imager because the cells
> are not necessarily contiguous ( because of yield problems there is
> redundancy and sections are added or subtracted to yield a usable device ).

As noted in the quote from the IS32 data sheet, it states that the sensor is
based on the Micron's standard DRAM - however addition of a treshold adjustment
suggests it's not exactly the same.

>> I have the datasheet for the IS32 scanned as well, which says "Improved cost
>> standards for binary image sensing (less than $.0003 / element) are delivered
>> through Micron's MT4264 64K dynamic RAM memory chip as the sensing device.
>> The OpticRAM(tm) image sensor is differentiated by packaging with a glass lid
>> (vs the opaque lid used in memory chips) and connection of the normally unused
>> pin 1 for optical threshold reference adjustment".


> They're also usually built into at least two 32K sections.

The data sheet also says:

  "Dual 128 x 256 element arrays"
  "32768 light sensing elements per array"

"Each of the two array on the chip contains 32,768 sensors arranged in 128 rows
by 256 columns of sensors. Thpical applications will utilize only one of the
arrays since the arrays are separated by an optical "dead zone" 120 microns wide."



Dave

--
dave09 (at)    Dave Dunfield
dunfield (dot) Firmware development services & tools: www.dunfield.com
com            Collector of vintage computing equipment:
               http://www.classiccmp.org/dunfield/index.html



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