Regenerative capacitor memory is a type of computer memory that uses the electrical property of capacitance to store the bits of data. Because the stored charge slowly leaks away, these memories must be periodically regenerated (i.e. read and rewritten, also called refreshed) to prevent data loss.
Other types of computer memory exist that use the electrical property of capacitance to store the data, but do not require regeneration. Traditionally these have either been somewhat impractical (e.g., the Selectron tube[1]) or are considered to be suitable only as read-only memory (e.g., EPROM, EEPROM/Flash memory[a]) since writing data takes significantly longer than reading.
History
editThe first regenerative capacitor memory built was the rotating capacitor drum memory of the Atanasoff–Berry Computer (1942). Each of its two drums stored thirty 50-bit binary numbers (1500 bits each), rotated at 60 rpm and was regenerated every rotation (1 Hz refresh rate).
The first random access regenerative capacitor memory was the Williams tube (1947).[2] As fitted to the first practical programmable digital computer, a single Williams tube held a total of 2560 bits, arranged in two 'pages'. One page was an array of thirty two 40-bit binary numbers, the capacity of a basic Williams-Kilburn Tube.[3] The refresh rate required varied depending on the type of CRT used.
The modern DRAM (1966) is a regenerative capacitor memory.[4]
Notes
edit- ^ Though not suited for use as a directly-accessible computer memory, Flash memory has developed into a widely used form of read-write mass storage with write speeds far exceeding competing technologies such as hard disks.
References
edit- ^ "Selectron tube". Virtual Exhibitions in Informatics. University of Klagenfurt. Retrieved 16 January 2018.
- ^ Rajchman, Jan (23 August 1946). "Lecture 43 - The Selectron". The 1946 Moore School Lectures. RCA Laboratories, Princeton: Moore School of Electrical Engineering. Archived from the original on 6 June 2013.
- ^ "The Manchester Mark 1", University of Manchester, archived from the original on 21 November 2008, retrieved 2020-06-09,
The Manchester Mark 1 Intermediary Version was based on two double-density Williams-Kilburn Tubes as main store, each with the capacity of two "page"s. A page was an array of 32 * 40 bits, the capacity of a basic Williams-Kilburn Tube
- ^ Klein, Dean A. "A History and Future of Memory Innovation". Semicon China. Micron Technology, Inc. Retrieved 16 January 2018.
Further reading
edit- Dekker, I.A.; Nieuwveld, W. A. C. (May 1964). "A capacitor memory for an analogue computer". Applied Scientific Research, Section B. 11 (3–4): 247–254. doi:10.1007/BF02922005. S2CID 108894706.