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43

That sounds a lot like the Cromemco Cyclops. Released in 1975, it used a modified1 MOS 1kbit DRAM2 to capture a 32×32 black and white or greyscale image. The memory cells were initially set to all 1s. As they were exposed to light they would progressively switch to 0s; the more light hitting a cell, the faster the transition4. By making multiple read ...


13

Alex Hajnal's answer pretty well describes what I believe is the first and eventually only commercial available camera that directly used RAM chips, the Cyclops (*1). It started out as a hobby level project, about the same time chip manufacturers did build the first dedicated CCD camera elements. CCDs were like the super hype of the 70s - at least to ...


8

We tried it in the lab, circa 1984. I worked with a hardware team and somewhere they'd read an article, the gist of which was something like: write all 1s to the DRAM ensure you don't have any hardware dynamic RAM refresh going on expose it for a given period read the decayed bits back I believe that we ended up having to write 1s or 0s depending on the ...


7

Sorry to come late to this party. One thing to note is that, in order to use the DRAM in the way that the Cromemco Cyclops does, it must be a design with a non-destructive read. The 4008 parts (both AMI and Mostek) are three transistor per cell DRAM designs with non-destructive reads. One other piece of information that I can provide is that, on an S-100 ...


5

The 4116 was likely designed during in an era (or semiconductor technology node) when self-timed-delay pre-charge-evaluate NMOS logic cascades were common. (e.g. rather than synchronously or edge clocked CMOS) The bit-line sense amps and wide column select mux had to consist of a large total gate area. Thus it would take quite awhile to precharge all of ...


3

Back around 1982, 1983 a friend of mine built a simple scanner using a 16k de-capped dram, probably a 4116. This was used on a Nascom 2 computer with a Nascom IMP dot matrix printer. The dram, along with a small bulb were fitted to a small cup which was attached to the print head. A sheet was put in the printer and software scanned by just printing spaces ...


2

As others have pointed out, the Cromemco Cyclops turned this into a (hobbyist) product. I've also found I could get reproducible transient bit flips in an unprogrammed EPROM. Shine a laser pointer onto the chip, and the cells under the light will flip, then flip back when the light goes away. I'm not sure of the mechanism, and I don't even remember whether ...


1

I will venture a guess. Imagine /CAS and the address bus are both registered outputs clocked by the same clock. The negative setup time allows a slight clock-to-output propagation delay discrepancy between the two outputs where /CAS falling may precede the address bits becoming stable. Moreover, there are other factors which may add propagation delay to ...


1

(Preface: leaving out the title column makes reading tables it a bit hard) It's all about translating labels and numbers into meaningful sentences. And there are different ways to tell a fact, and thus more nuanced details. Timing does describe relations. Here it's about the fact, that CAS must be released at least 20 ns before RAS can be pulled again. It'...


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