Write-only memory (joke)
Write-only memory (WOM) is the opposite of read-only memory (ROM). By some definition, a WOM is a memory device which can be written but never read. Since there should be no practical use for a memory circuit from which data cannot be retrieved, the concept is most often used as a joke or a euphemism for a failed memory device.
The first use of the term is generally attributed to Signetics in 1972. Signetics published some write-only memory literature as the result of an inside practical joke, which is frequently referenced within the electronics industry, a staple of software engineering lexicons, and included in collections of the best hoaxes.
The datasheet was created "as a lark" by Signetics engineer John G ‘Jack’ Curtis and was inspired by a fictitious and humorous vacuum tube datasheet from the 1940s. It was seen as "an icebreaker" and was deliberately included in the Signetics catalog.
Roy L Twitty, a Signetics PR person, released a tongue-in-cheek press release touting the WOM on April 1, 1973.
Instead of the more conventional characteristic curves, the 25120 "fully encoded, 9046×N, Random Access, write-only-memory" data sheet included meaningless diagrams of "bit capacity vs. Temp.", "Iff vs. Vff", "Number of pins remaining vs. number of socket insertions", and "AQL vs. selling price". The 25120 required a 6.3 VAC Vff (vacuum tube filament) supply, a +10 Vcc (double the Vcc of standard TTL logic of the day), and Vdd of zero volts (i.e. ground), ±2%. It was specified to run between 0 and −70°C.
In 1982, Apple published their official Apple IIe Reference Manual (part number A2L2005), which included two references to write-only memory.
On page 250:
On page 233:
In 1995 Computer Contradictionary book, it reports EWOM, or Erasable Write-Only Memory (an analogy of EPROM), a memory copyrighted by IBM (Irish Business Machines), which allows the data to be written into and then erased from, for memory re-use.
With the explosive growth of the amount of video data available both online and in private use, there emerged a common joke that video tapes and other video media are "write only memory", because without efficient means of search and retrieval for video data archives very little is viewed after recording.
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