Editing Whirlwind I (section)

===Magnetic-core memory===
[[File:8863-Project-Whirlwind-CRMI.JPG|thumb|Circuitry from core memory unit of Whirlwind]]
[[File:8868-Project-Whirlwind-CRMI.JPG|thumb|Core stack from core memory unit of Whirlwind]]
[[File:Project Whirlwind - core memory, circa 1951 - detail 1.JPG|thumb|[[Project Whirlwind]] core memory, circa 1951]]
Jay Forrester was desperate to find a suitable memory replacement for his computer. Initially the computer only had 32 words of storage, and 27 of these words were [[read-only memory|read-only]] registers made of [[toggle switch]]es. The remaining five registers were [[Flip-flop (electronics)|flip-flop]] storage, with each of the five registers being made from more than 30 [[vacuum tube]]s. This "test storage", as it was known, was intended to allow checkout of the processing elements while the main memory was not ready. The main memory was so late that the first experiments of tracking airplanes with live [[radar]] data were done using a program manually set into test storage. Forrester came across an advertisement for a new magnetic material being produced by a company. Recognizing that this had the potential to be a data storage medium, Forrester obtained a workbench in the corner of the lab, and got several samples of the material to experiment with. Then for several months he spent as much time in the lab as he did in the office managing the entire project.

At the end of those months, he had invented the basics of [[magnetic-core memory]] and demonstrated that it was likely to be feasible. His demonstration consisted of a small core plane of 32 cores, each three-eighths of an inch in diameter. Having demonstrated that the concept was practical, it needed only to be reduced to a workable design.  In the fall of 1949, Forrester enlisted graduate student William N. Papian to test dozens of individual cores, to determine those with the best properties.<ref name="ProjectWhirlwind">{{Cite web |url=https://archive.org/details/bitsavers_mitwhirlwirlwindACaseHistoryInContemporaryTechnolo_14582082 |title=Project Whirlwind |author-last1=Redmond |author-first1=Kent C. |author-last2=Smith |author-first2=Thomas M. |date=November 1975 |publisher=The MITRE Corporation |page=11.6 |access-date=2016-07-22}}</ref> Papian's work was bolstered when Forrester asked student [[Dudley Allen Buck]]<ref>{{cite web|url=http://dome.mit.edu/bitstream/handle/1721.3/38908/MC665_r04_E-504.pdf | title=FERROELECTRICS FOR DIGITAL INFORMATION STORAGE AND SWITCHING |access-date=2023-10-19}}</ref><ref>{{cite web|url=http://dome.mit.edu/bitstream/handle/1721.3/39012/MC665_r04_E-460.pdf |title=THE FERROELECTRIC SWITCH |access-date=2023-10-19}}</ref><ref>{{Cite web|url=https://spectrum.ieee.org/computing/hardware/dudley-bucks-forgotten-cryotron-computer|archive-url=https://web.archive.org/web/20140326182703/http://spectrum.ieee.org/computing/hardware/dudley-bucks-forgotten-cryotron-computer|url-status=dead|archive-date=March 26, 2014|title = Full Page Reload}}</ref> to work on the material and assigned him to the workbench, while Forrester went back to full-time project management. (Buck would go on to invent the [[cryotron]] and [[content-addressable memory]] at the lab.)

After approximately two years of further research and development, they were able to demonstrate a core plane that was made of 32 by 32, or 1024 cores, holding 1024 bits of data. Thus, they had reached the originally intended storage size of an electrostatic tube, a goal that had not yet been reached by the tubes themselves, only holding 512 bits per tube in the latest design generation. Very quickly, a 1024-word core memory was fabricated, replacing the electrostatic memory. The electrostatic memory design and production was summarily canceled, saving a good deal of money to be reallocated to other research areas. Two additional core memory units were later fabricated, increasing the total memory size available.