Editing DEC Alpha (section)

===Improved models===
The first few generations of the Alpha chips were some of the most innovative of their time.
* A pre-production model, designated ''EV3'', was used in a prototype system named the ''Alpha Demonstration Unit'' (ADU). ADUs were used to port operating systems to the Alpha architecture. One key difference between the EV3 and later models was the absence of a floating-point unit.<ref>{{cite journal|url=https://vmssoftware.com/docs/dtj-v04-04-1992.pdf|title=The Alpha Demonstration Unit: A High-performance Multiprocessor for Software and Chip Development|author1=Charles P. Thacker|author2=David G. Conroy|author3=Lawrence C. Stewart|journal=Digital Technical Journal|volume=4|issue=4|year=1992|access-date=2024-04-06|page=51}}</ref>
* The first version, the ''[[Alpha 21064]]'' or ''EV4'', is the first [[CMOS]] microprocessor whose operating frequency rivalled higher-powered [[Emitter coupled logic|ECL]] minicomputers and mainframes. 
* The second, ''21164'' or ''EV5'', is the first microprocessor to place a large secondary cache on-chip.<ref>{{cite journal |title=Internal Organization of the Alpha 21164, a 300-MHz 64-bit Quad-issue CMOS RISC Microprocessor |author1=John H. Edmondson |author2=Paul I. Rubinfeld |author3=Peter J. Bannon |author4=Bradley J. Benschneider |author5=Debra Bernstein |author6=Ruben W. Castelino |author7=Elizabeth M. Cooper |author8=Daniel E. Dever |author9=Dale R. Donchin |author10=Timothy C. Fischer |author11=Anil K. Jain |author12=Shekhar Mehta |author13=Jeanne E. Meyer |author14=Ronald P. Preston |author15=Vidya Rajagopalan |author16=Chandrasekhara Somanathan |author17=Scott A. Taylor |author18=Gilbert M. Wolrich |journal=Digital Technical Journal |volume=7 |issue=1 |year=1995 |pages=119–135 |quote=large, on-chip, second-level, write-back cache |citeseerx=10.1.1.38.9551}}</ref>
* The third, ''21264'' or ''EV6'', is the first microprocessor to combine both high operating frequency and the more complicated [[out-of-order execution]] microarchitecture. 
* The ''21364'' or ''EV7'' is the first high performance processor to have an on-chip [[memory controller]].<ref>{{cite book
|quote=21364 ... first high performance processor to have an onchip memory controller.
|title=Structured Computer Organization
|url=https://books.google.com/books?isbn=147842673X
|isbn=978-1478426738 |date=2016|last1=Reviews
|first1=C.T.I
}}</ref> 
* The unproduced ''[[Alpha 21464|21464]]'' or ''EV8'' would have been the first to include [[simultaneous multithreading]], but this version was canceled after the sale of DEC to [[Compaq]]. The ''[[Alpha 21464#Tarantula|Tarantula]]'' research project, which most likely would have been called ''EV9'', would have been the first Alpha processor to feature a [[vector processor]] unit.<ref name='Tarantula'>{{cite conference
  | author1 = Roger Espasa
  | author2 = Federico Ardanaz
  | author3 = Julio Gago
  | author4 = Roger Gramunt
  | author5 = Isaac Hernandez
  | author6 = Toni Juan
  | author7 = Joel Emer
  | author7-link = Joel Emer
  | author8 = Stephen Felix
  | author9 = Geoff Lowney
  | author10 = Matthew Mattina
  | author11 = Andre Seznec
  | year = 2002
  | editor = Danielle C. Martin
  | others = Joe Daigle/Studio Productions
  | title = Tarantula: A Vector Extension to the Alpha Architecture
  | url = http://systems.cs.colorado.edu/ISCA2002/
  | conference = 29th Annual International Symposium on Computer Architecture (ISCA '02)
  | conference-url = http://systems.cs.colorado.edu/ISCA2002
  | book-title = Proceedings: 29th Annual International Symposium on Computer Architecture (ISCA '02)
  | pages = 281–292
  | publisher = IEEE Computer Society
  | location = Los Alamitos, Calif
  | isbn = 0-7695-1605-X
  | doi = 10.1109/ISCA.2002.1003586
  | url-status = live
  | archive-url = https://web.archive.org/web/20071004172421/http://systems.cs.colorado.edu/ISCA2002/
  | archive-date = 2007-10-04
  | access-date = 2007-10-04
}}</ref>

A persistent report attributed to DEC insiders suggests the choice of the ''AXP'' tag for the processor was made by DEC's legal department, which was still smarting from the [[Vax (brand)#Trademark conflict|VAX trademark]] fiasco.<ref>{{cite web |title=The VAX Vacuum 
|url=https://groups.google.com/d/topic/comp.os.vms/8ptFdR3KYxg
|quote=... legally, if DEC had used VAX in the U.S. before that ..... "reasonable person" has no difficulty distinguishing between the two uses}}</ref> After a lengthy search the tag "AXP" was found to be entirely unencumbered. Within the computer industry, a joke got started that the acronym ''AXP'' meant "Almost eXactly PRISM".<ref>{{Cite mailing list |mailing-list=Linux kernel mailing list |author=Chad Page |title=The meaning of AXP (was Re: ALPHA ambiguity) |date=30 April 1996 |url=https://lkml.org/lkml/1996/5/1/47 |access-date=2024-08-29}}</ref>