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It's funny. Laugh. Technology Hardware

The Joker Behind the Signetics 25120 Write-Only Memory Chip Hoax 100

Posted by Soulskill from the things-the-USPTO-would-totally-issue-a-patent-for dept.
New submitter st1lett0 writes: Now and in years past, electronic engineers and hobbyists alike have enjoyed the classic 1972 April Fool's joke by Signetics of the Signetics 25120 Write-Only Memory chip. Now it seems that the previously anonymous practical joker has identified himself and stepped forward with new information to correct and complete the story.
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The Joker Behind the Signetics 25120 Write-Only Memory Chip Hoax More

The Joker Behind the Signetics 25120 Write-Only Memory Chip Hoax

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  • Joke? They're real! (Score:5, Funny)

    by 91degrees ( 207121 ) on Tuesday December 16, 2014 @05:23AM (#48607827) Journal
    These days used for cheap knock-off memory sticks.

    • Re: (Score:3, Funny)

      by smittyoneeach ( 243267 ) *
      Whereas modern legislation is of the Write Once, Read & Think Heaven's Leaving Everyone Short Shrifted (WORTHLESS) variety.

    • Re: (Score:1)

      by Anonymous Coward

      LOL, obligatory Slashgear link [slashgear.com]

    • Government agencies like CIA and NSA use Signetics 25120 to store very sensitive information. After writing the data, the original source is then destroyed...

      • Re: (Score:2)

        by Meski ( 774546 )
        <puts hand up> I volunteer to write the retention schedule for it. Might as well handle redaction whilst I'm doing it. </wally>

    • Re: (Score:2)

      by Rei ( 128717 )

      I think the problem is just misconceptualized. Think of read-only memory, like say DVDs. They're not *100* read-only. Data is written to them once in an irreversible manner before their operational life begins using an alternative write mechanism, and then during their design life they're read-only. If you apply the same paradigm to write-only memory, it's perfectly reasonable for, say, a datalogger: data is written during the operation of the device, then when the device has completed its task, the memory

      • I think the problem is just misconceptualized. Think of read-only memory, like say DVDs. They're not *100* read-only. Data is written to them once in an irreversible manner before their operational life begins using an alternative write mechanism, and then during their design life they're read-only. If you apply the same paradigm to write-only memory, it's perfectly reasonable for, say, a datalogger: data is written during the operation of the device, then when the device has completed its task, the memory is retrieved and read in an irreversible manner.

        I think you missed the point - if you can read it, then it's not write-only memory.

        • I think you missed the point. If you can write to it, then it's not Read Only Memory. Yet, somehow, at some point, all ROM was written to, or there would be nothing to read later.

          • I think you missed the point. If you can write to it, then it's not Read Only Memory. Yet, somehow, at some point, all ROM was written to, or there would be nothing to read later.

            Actually mask roms are never written to. The circuits are hard-wired. If the mask is defective, you throw the chip out.

          • Re: (Score:1)

            by Khyber ( 864651 )

            I think you failed basic semiconductor electronics. ROMs are lithographically etched with the code hard-wired in the design. Back then, the only way to erase was to expose the semiconductor ROM chip to UV light to destroy the chip. That's why they came with clear windows with a sticker over them. Remove sticker, zap with UV for a few seconds, dead ROM.

            • ROMs are lithographically etched...

              A.k.a. written.

            • Re: (Score:1)

              by Anonymous Coward

              You are confusing mask ROMs and EPROMs. EPROMs were writable, but had a window for erasing them with UV light. That did not destroy the EPROM; it simply changed all the data to 0xff. The EPROM could then be programmed with new data. Note that it was called "programming" the EPROM, not writing to it. Mask ROMs could not be erased, and did not have windows.

              • For non volatile memories - EPROMs, EEPROMs, Flash, erasing means setting all the data cells (within a specified area) to '1'. Programming means setting certain data cells in a given address with 0. Writing means erasing certain data cells to 1 and then programming the bits that need to be made 0 to 0.

              • Re: (Score:2)

                by Meski ( 774546 )
                And were fantastically cheaper if you bought billions of them <carl sagan voice> Later EPROMS came without windows and were called OTP (one time programmable) - these hit a good price point - do your dev with the quartz windowed ones, and small production runs with OTP
            • Those were UVROMs. ROMs were series of rows and columns, with the columns that needed to be 0 connected to the ground by diodes, and the ones that needed to be 1 left floating. As others said above, they were originally etched during time of manufacture, and once out of fab and package/test, they were done. No writing evar!

            • Re: (Score:1)

              by tibit ( 1762298 )

              You confuse EPROM, PROM and ROM. A mask-programmed ROM cannot be erased without destroying it. UV light will do nothing to a ROM. A PROM uses cells with electrically-destructible fuses or cells with stored electrical charge - it is electrically programmed, not mask-programmed. UV light will do nothing to a fuse-based PROM, but will erase the charge-based PROM. The charge-based PROMs are also called OTP EPROM (one time programmable, but not eraseable, so a misnomer). The addition of a quartz window turns a n

            • I think you failed basic semiconductor electronics. ROMs are lithographically etched with the code hard-wired in the design. Back then, the only way to erase was to expose the semiconductor ROM chip to UV light to destroy the chip. That's why they came with clear windows with a sticker over them. Remove sticker, zap with UV for a few seconds, dead ROM.

              You are describing UV erase EPROM. Not mask ROM.

          • Re: (Score:2)

            by unitron ( 5733 )

            But the article is about Write-Only Memory. It can't be read, it can only be written to.

        • Re:Joke? They're real! (Score:5, Insightful)

          by BarefootClown ( 267581 ) on Tuesday December 16, 2014 @12:14PM (#48609845) Homepage

          From the perspective of the CPU, a printer is write-only memory.

          • Re: (Score:2)

            by tibit ( 1762298 )

            Not necessarily. Some modern color printers have built-in optical scanners used for color alignment. They certainly can read what they wrote on the image transfer belt. I have one like that.

      • Except that DVDs are no more written than vinyl records. They're stamped with a non-adjustable template during the manufacturing process. Perhaps you are thinking of DVD-Rs, but that's a write-once media, not read-only.

      • Re: (Score:2)

        by dgatwood ( 11270 )

        I think the problem is just misconceptualized. Think of read-only memory, like say DVDs. They're not *100* read-only. Data is written to them once in an irreversible manner before their operational life begins using an alternative write mechanism, and then during their design life they're read-only. If you apply the same paradigm to write-only memory, it's perfectly reasonable for, say, a datalogger: data is written during the operation of the device, then when the device has completed its task, the memory

    • I hear that next year they are coming out with an Erasable Write Only Memory so you can re-use it when you run out of memory.

    • I always created my best APL programs with write only memory.

  • From TFA:

    ...If you look on the last note on the 25120 data sheet, I had included, âoeDue credit to EIMAC for inspiration.â.

    I had always admired an EIMAC high powered vacuum tube spoof data sheet put out by Eitel-McCullough,Inc. I saw it when I was a teen Ham Operator and must have memorized it. That was in the late 1940â(TM)s.

    So far I havenâ(TM)t relocated a copy of the EIMAC spoof data sheet. You need it to see the relevance. It pictured a melted EIMAC power tube and offered humorous specifications. If you know where there is a copy, let me know ...

    Anyone here got a copy of the EIMAC Spoof Data Sheet?

    Wanna share with us?

  • I've been waiting to find out about this one. Waiting a long time.

  • 31 mega pixel background image (Score:3)

    by wonkey_monkey ( 2592601 ) on Tuesday December 16, 2014 @06:18AM (#48607919) Homepage

    Jeez, I know we've all got super-fast broadband and the like, but is there really any good reason to have a 31 megapixel background image?

    Remember, every byte transmitted hastens the heat death of the universe!

    • Jeez, I know we've all got super-fast broadband and the like, but is there really any good reason to have a 31 megapixel background image?

      Remember, every byte transmitted hastens the heat death of the universe!

      Actually, that image is the actual add from the magazine!
      Thanks for pointing that out... the schematic is hilarious!

  • So it was him all along! (Score:3)

    by excelsior_gr ( 969383 ) on Tuesday December 16, 2014 @06:27AM (#48607927)

    I just knew that the Jocker was behind all this! It's about time we locked him back in Arkham and threw away the key!

    Oh, wait...

  • A memory chip that can only be written to could be quite secure. And before you laugh obviously there would have to be another way to retrieve the data - perhaps plugging it into a special board with completely different voltages or even taking the lid off - that the machine its sitting in would be able to do. I could see a use for this sort of thing in espionage. Store the data on this chip and send it off but if its intercepted the enemy can't figure out how to get the data out of it since any read operat

    • Re: (Score:1)

      by Anonymous Coward

      Well, maybe not, but it won't happen on *this* device. Did you see the block diagram? The data-in line is simply inverted twice and presented as the data-out line without actually going into the memory cells at all. Unless it uses some mystical field-effect-at-a-distance technique, it's not going to couple the data-input signal to any of the memory. Just as well. It keeps the data safe from being recorded.

      This device could point to the possibility of a real device. Even better is to write to the memor

  • AH, the good old days (Score:1)

    by Anonymous Coward

    Remember when electrical engineering in the West was still a viable career choice? With some semblance of social worth, stability and employer-employee respect?

    Can you imagine this kind of joke happening today?

    1) You think the kind of student that studies EE these days is actually interested in electronics and could appreciate the joke?
    2) That an employer/HR dep't would tolerate these kinds of hijinks?

    Just seems electrical engineering is just a gigantic faceless operation now, more of a nuisance than the ce

    • Re: (Score:1)

      by Anonymous Coward

      damn, my 2nd choice was being a milkman. gonna go kill myself now.

    • I was wondering why someone was still employed after reading the story myself. Next they made an ad?? Yeah heads would roll in today's more hostile work environment.

      Maybe I just worked for shitty employers recently? But I heard back then you stayed with a company for 30 years. So different today where firing 15% every year is the new rage. Sigh ...

      • I'd gladly trade my modern computer and phone for the lifestyle of the 1960s-1990s. Something happened quite recently to make work much more hostile and corrosive.

      • In older times companies were proud of their real leaders (NOT referring to management necessarily). That included engineers who had major accomplishments and who had earned respect for a lifetime of work. Those are the kind of people who could make such a joke and client's customers would know it was that person's joke, because they trusted that leader and had long success with their work.

        Now companies only brag about their C?O people, everyone else is nameless faceless disposable droid

  • 1N000 (Score:5, Funny)

    by Anne Thwacks ( 531696 ) on Tuesday December 16, 2014 @08:16AM (#48608179)
    I used to have a whole box of 1N000 smoke-emitting-diodes.

    They are easily recognised by the colour code "three black bands on a black background".

    They are normally used to supply the "magic smoke" required by electronic systems to operate at full power, but I believe there are other uses.

    I had a data sheet for a Motorola WOM as well - I believe from about the same date.

  • for my backups. Backup speed increases significantly and only slightly reduces the likelihood that I will be able to restore the data.

    • Most of my DVR contents are stored using WOMEN (write once maybe erase never) memory.

      My fault for installing a 12TB RAID Array.

      Now my wife records everything, but watches almost none of it.

  • I invented the hoax "Free to Play".

  • more useful than Intel's EEPROMs (Score:5, Interesting)

    by dltaylor ( 7510 ) on Tuesday December 16, 2014 @08:50AM (#48608353)

    There was a time when some of Intel's EEPROMs (1702As, IIRC, but, maybe, 2048s) were write/read-maybe. Seems some materials guy got a really good deal on some clay to make the ceramic carrier. Only problem was that the clay was radioactive enough for the emissions to change the stored data. Back in those days (1702s were only 256 BYTES), the storage cells weren't all that robust, so enough decay particles hitting the cells could flip them.

    Think THAT didn't take a while to track down?

  • I wasn't orginal? (Score:3, Interesting)

    by Ronin Developer ( 67677 ) on Tuesday December 16, 2014 @09:02AM (#48608403)

    Bumming...I invented the Write Only Drive while at college. Now, it looks like I infringed on the Patent. Mine, however, used the Pauli-Exclusion and Heisenberg Uncertainty Principles to store information on each atom. Problem was, we hadn't figured out how to get the data back out (it was just a s SCSI cable going into a black box. I think we just needed Heisenberg Compensators.

    Even though we published our "Announcement" it during our April's Fools edition of our Newsletter, we received one call from a company wanting to commercially build it. We had to explain it was a joke.

  • Most people think of WORM memory when they read this stuff.

    I'm autistic, and I totally understand why people get confused about this. If you want to be really rigorous in how you talk, that's fine, but realize that not everyone is going to be that way.

    I used to get pissed that people call the United States a democracy, since that word isn't in any of the major documents. Then I took the stick out of my ass.

    Not trying to insult anyone, just saying.

    • Re: (Score:1)

      by Anonymous Coward

      What did you do with the stick? Where is it now?

  • Second story on that site (Score:5, Interesting)

    by Anonymous Coward on Tuesday December 16, 2014 @09:17AM (#48608479)

    There is a second story on that site. He wrote the spec and they ignored him on wikipedia. He can even produce the original draft copies. They told him to pound sand and 'just go make a blog about it'.

    That is sad.

    • I've dealt with the moderator people at Wikipedia myself. Thanks to that experience, I'll never ever donate to the Wikipedia foundation. They may as well just stop sending the ads - because I'm not interested.

  • Write-only languages (Score:5, Funny)

    by quenda ( 644621 ) on Tuesday December 16, 2014 @09:43AM (#48608627)

    Unlike WOM, write-only languages are all too real.
    I can't even read my own PERL scripts if they are more than a week old.

    • Unlike WOM, write-only languages are all too real. I can't even read my own PERL scripts if they are more than a week old.

      ever thought of... ya' know... commenting your code?

      • Commenting individual lines of code, is for the most part, a bad idea. Code should be clear enough, such that somebody well versed in the programming language knows what is going on without the help of comments. Commenting functions so that you know what they do is another matter entirely, and should be done. But if a language doesn't let you write clear enough such that you can understand it later without comments, I would highly suggest using another language. If you rely on comments to tell you what t
    • Yeah, it's a shame that the ideal use case for the 25120 didn't come along for several more years.
  • Did Batman catch him?
  • There were other component hoaxes.

    BD-1 Battery Discharger, also had a product spec printed. Marketing actually heard from a customer who wanted samples.

    To compliment the Light Emitting Diode (LED), a company offered the Dark Emitting Diode (DED).

    Hard to top the WOM though. I actually used that term in a meeting involving computers. Reaction was deer in the headlights from the IT folks. Had to quickly clue them in.
    • Also the "Little Wonder" fuse blower - a NO switch shorting the mains supply through the fuse "under test". My grandfather claimed he worked for a company that sold them - but he also claimed loads of things too!

  • That's not a joke! (Score:5, Funny)

    by putaro ( 235078 ) on Tuesday December 16, 2014 @11:08AM (#48609245) Journal

    How do you think /dev/null is implemented?

    • That is in older machines; with the advent of virtualization and the possibility the machine might be virtualized, the device is now fully implemented in software with a FINO queueing algorithm (first in never out).

  • The Darkness Emitting Arsenide Diode (DEAD).

    The Electro-Voice Rearaxial Softspeaker from about 1966 is a real hoot.

    Some microwave components company put out a "Our Company" pamphlet that was a real knee-slapper. It had the usual corporate description of operations with 1920's era photographs. "Our retirement plan...." a graveyard.

  • So, to squeeze all the memory in 16 bits of address line, certain areas were overlays. In particular, there was an overlay of video memory that overlapped app memory space. How did they work this out? Once your program was running and you mapped the additional memory in, any writes from user code went to the memory (no self modifying code) and any reads came from the video rasterizer.

    From the perspective of your program, write only memory.

  • Those others are great fun. 8-)

    But the 25120 WOM chip was the only one I know of that was in the actual company catalog, has an actual copyright and the data sheet could be ordered from the company!

    And it actually created "buzz" and sales for the company (for other chips).

    One guy I knew, insisted for years that it was real... 8-P

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