Read-mostly memory

Read-mostly memory (RMM) is a type of memory that can be read fast, but written to only slowly.

Historically, the term was used to refer to different types of memory over time:

In 1970, it was used by Intel and Energy Conversion Devices to refer to a new type of amorphous and crystalline nonvolatile and reprogrammable semiconductor memory (phase-change memory aka PCM/PRAM).^[1][2] However, it was also used to refer to reprogrammable memory (REPROM)^[3] and magnetic-core memory.^[4]

The term has mostly fallen into disuse, but is sometimes used referring to electrically erasable programmable read-only (EEPROM) or flash memory today.^[5]

See also

• Read-only memory (ROM)
• Read–write memory (R/W)
• Programmable read-only memory (PROM)
• Random-access memory (RAM)

References

1. Neale, Ronald "Ron" G.; Nelson, D. L.; Moore, Gordon Earle (1970-09-28). "Nonvolatile and reprogrammable, the read-mostly memory is here" (PDF). Electronics. McGraw-Hill. pp. 56–60. S2CID 137556114. Archived from the original (PDF) on 2022-07-07. Retrieved 2020-07-01.
2. Handy, Jim (2018-01-17). "Original PCM Article from 1970". The Memory Guy, Objective Analysis, Semiconductor Market Research. Archived from the original on 2020-07-01. Retrieved 2020-07-01.
3. Bode, Arndt [in German]; Händler, Wolfgang (1980). Written at Erlangen, Germany. Rechnerarchitektur: Grundlagen und Verfahren (in German) (1 ed.). Berlin / Heidelberg, Germany; New York, USA: Springer-Verlag. p. 102. ISBN 3-540-09656-6. Retrieved 2020-07-01. […] RMM (Read mostly memory) oder REPROM (Reprogrammable memory): Semifestspeicher, bei denen das Schreiben möglich, jedoch wesentlich aufwendiger als das Lesen ist (meist um einige Zehnerpotenzen). […] (xii+278+2 pages)
4. Klar, Rainer (1989) [1988-10-01]. "Tabelle 6.2 Beispiele mikroprogrammierter Rechner" [Table 6.2 Examples of micro-programmed computers]. Digitale Rechenautomaten – Eine Einführung in die Struktur von Computerhardware [Digital Computers – An Introduction into the structure of computer hardware]. Sammlung Göschen (in German). Vol. 2050 (4th reworked ed.). Berlin, Germany: Walter de Gruyter & Co. p. 223. ISBN 3-11011700-2. […] Honeywell H4200 […] 1966 […] Kernspeicher […] 2 Kerne/Bit […] RMM: Read-mostly-Memory, d.h. Speicher mit langsame[m] Schreiben, aber schnellem Lesen […] (320 pages)
5. Astels, Dave (2020-07-01) [2018-05-02]. "Read Mostly Memory". adafruit. Archived from the original on 2020-07-01. Retrieved 2020-07-01.

Further reading

• United States 4199692A, "Amorphous non-volatile ram"