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Casio-F-91W die-shot

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Re: Casio-F-91W die-shot

#82

Post by [deleted] »

Ecco wrote: post #2

Dumb question: is it legal to share a die shot like this one? What does copyright law say about this? I mean, yes, the author took the photo himself but what about the underlying material? Can I share a photo of an entire book? Do I own the copyright to a photo of a painting?

[deleted]

Re: Casio-F-91W die-shot

#85

Post by aidenn0 »

vasqw wrote: post #12

I bought one of those recently and I was surprised by how inaccurate it was. It drifted like 15 seconds every month. From what I've been reading, that is normal, but I was surprised - with all the technological advances that we have it is odd to think that cheap timekeeping is not a solved problem yet! Also: how is the software of these watches without a CPU designed? Is it something like Verilog or whatever?

~1s per day is normal for a non-temperature-compensated quartz crystal. The cheap solution is to just sync to LF time transmissions (or GPS if not running on battery power).

The F-91W might not actually have anything resembling software; just fixed function mixed-signal circuitry, but I haven't investigated it. Given the timing of its release, it's possible that an HDL was used, but also possible it was designed at the circuit level with CAD. The F-87W (which the 91W replaced) predates either VHDL or Verilog.

Re: Casio-F-91W die-shot

#87

Post by aidenn0 »

dougSF70 wrote: post #52
jimmyjazz14 wrote: post #48

Earlier quoted context omitted.

I don't really understand your comment about avoiding Seiko (and yes as a Seiko collector I'm a bit triggered). In my experience Seiko makes absolutely great quality watches still with maybe the only issues generally being the occasional misaligned chapter ring though I pretty much only collect Seiko mechanical watches so maybe the situation is different with their quartz watches. Citizen also makes some particularly…

Seiko 5 automatic movement is on a par with the Rolex automatic movement according to my friend who is an official Rolex repairer.

Quality of Seiko 5 is pretty good, but IIRC the Rolex movement is more compact.

Re: Casio-F-91W die-shot

#88

Post by omoikane »

kens wrote: post #39
aliljet wrote: post #28

This is a remarkably interesting image. How do these guys even get these shots? I'd love to do this on all kinds of things at home..

For die photos, you want a metallurgical microscope, one that shines light down through the lens. A typical microscope shines the light from underneath, which works well for biological samples, but not so well for chips. The tricky part is decapping the chip. The easy way is to get a ceramic package, which you can decap with a chisel. Or a metal can, which you can open with a hacksaw. With a standard epoxy package, y…

This same site has an article on laser decapsulation not too long ago:

https://zeptobars.com/en/read/laser-decapsulation-fail-not-s...

It appears to not work so well, but the video looked very cool.

Re: Casio-F-91W die-shot

#89

Post by somat »

vasqw wrote: post #12

I bought one of those recently and I was surprised by how inaccurate it was. It drifted like 15 seconds every month. From what I've been reading, that is normal, but I was surprised - with all the technological advances that we have it is odd to think that cheap timekeeping is not a solved problem yet! Also: how is the software of these watches without a CPU designed? Is it something like Verilog or whatever?

A fair assessment, but I find it funny that 15 seconds per month is considered inaccurate, analog watches would kill for that sort of accuracy, a railroad quality pocket watch for example must loose no more than 30 seconds per week. I would guess that as smartphones are replacement for the pocketwatch, The way their network connected, never drift clock works becomes the new normal.

I have to admit, for my day to day use I am happy if I am less than five minutes off.

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