Robert Bruce Thompson; Barbara Fritchman Thompson (24 July 2003). PC Hardware in a Nutshell (3rd ed.). O'Reilly & Associates, Inc. p. 1.1 PCs Defined. ISBN0-596-00513-X. Archived from the original on July 11, 2011. Retrieved January 4, 2011.
"Chapter 3 PC System". PC 2001 System Design Guide(PDF). Intel Corporation and Microsoft Corporation. p. 52. Retrieved 2023-06-03. SYS–0047. A20M# is always de-asserted (pulled high) at the processor
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Robert Bruce Thompson; Barbara Fritchman Thompson (24 July 2003). PC Hardware in a Nutshell (3rd ed.). O'Reilly & Associates, Inc. p. 1.1 PCs Defined. ISBN0-596-00513-X. Archived from the original on July 11, 2011. Retrieved January 4, 2011.
