Mnemonic memory circuit
A mnemonic memory circuit was a 23rd century computer technology used for accessing data in information storage devices.

In 1930, after having traveled back in time from the year 2267 through the sentient time portal known as the Guardian of Forever, Spock attempted to construct a mnemonic memory circuit using period components, in order to access information stored on his tricorder taken from the Guardian, to ascertain how Doctor McCoy had changed history. Spock was frustrated in his attempts, however, equating the materials he was using to build the circuit to "stone knives and bearskins." 

Nevertheless, by temporarily overloading the circuit, Spock was able to access the information and determine that, in order for Captain Kirk and himself to restore the timeline, Edith Keeler, the social worker they received aid from, must be allowed to die. ()

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Computer technology