Write-Only-Memory (1972)

Let’s start with one of the classics from the early 1970’s, namely, the write-only-memory (WOM). It was the opposite of read-only-memory (ROM), which is used in all computer systems. The joke was that a WOM device could be written to but never read from memory. Initially, the WOM was used as a euphemism for a failed memory device.

The write-only-memory device first appeared in a practical joke data sheet from Signetics in 1972.  The company was a U.S. integrated circuit (IC) electronics manufacturer founded in 1961, which was bought by Philips in 1975 and incorporated into Philips Semiconductors (now NXP). Signetics was perhaps best known for its ubiquitous 555 timer IC.

As with most data sheet of the time, the Signetics sheet listed the characteristic curve of the useless device. But instead of the more conventional characteristic curves, the 25120 write-only-memory data sheet included meaningless diagrams of “bit capacity vs. temperature.”, “Iff vs. Vff”, “Number of pins remaining vs. number of socket insertions”, and “AQL (acceptable quality limit) vs. selling price”. Each of these specifications was funny in itself. Equally humorous were the footnotes on the specification:

1. “Neu” channel 16V CMOS enhances or depletes regardless of gate polarity, either simultaneously or randomly. Sometimes not at all.

2. “S.O.S” copyrighted U.S. Army Commissary, 1940.

3. Not applicable.  Of course, this was extremely applicable.

4. You can somehow drive these inputs from TTL, the method is obvious.

5. Measure at 1MHz, 25mvac, 1.8pf in series.

6. For filaments, what else!

7. You have a dirty mind. S.E.X. is a Signetics Extra Secret process. “One Shovel Full to One Shovel Full’” patented by Yagura, Kashkooli, Converse and AL, Circa 1921.

8. J. Kana calls it design (we humor him).

9. See “Modern Production Techniques” by T. Arrieta (not yet written).

10. Final until we got a look at some actual parts.

11. Coffee breaks and lunch hours.

12. Due credit to EIMAC for inspiration.

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