WDC 65C21 - Revision history

Idea at 05:28, 29 September 2026

2026-09-29T05:28:50Z

← Older revision		Revision as of 05:28, 29 September 2026
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	~~{{Short description\|Peripheral Interface Adapter made by Western Design Center}}~~
	~~<!-- Please do not remove or change this AfD message until the discussion has been closed. -->~~
	~~{{Article for deletion/dated\|page=WDC 65C21\|timestamp=20260918153854\|year=2026\|month=September\|day=18\|substed=yes\|help=off\|outcome=redirecting\|target=Western Design Center}}~~
	~~<!-- Once discussion is closed, please place on talk page: {{Old AfD multi\|page=WDC 65C21\|date=18 September 2026\|result='''keep'''}} -->~~
	~~<!-- End of AfD message, feel free to edit beyond this point -->~~
	~~{{More citations needed\|date=September 2026}}~~
	[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]		[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]
	The '''W65C21S''' is a Peripheral Interface Adapter (PIA) for use with WDC's 65xx and other 8-bit microprocessor families. It was produced by [[Western Design Center\|Western Design Center (WDC)]].		The '''W65C21S''' is a Peripheral Interface Adapter (PIA) for use with WDC's 65xx and other 8-bit microprocessor families. It was produced by [[Western Design Center\|Western Design Center (WDC)]].

Idea: Idea moved page Archive:WDC 65C21 to WDC 65C21

2026-09-29T05:28:36Z

Idea moved page Archive:WDC 65C21 to WDC 65C21

← Older revision	Revision as of 05:28, 29 September 2026
(No difference)

Waza: 29 revisions imported: AfD preservation: WDC 65C21 (CC BY-SA)

2026-09-29T05:14:54Z

29 revisions imported: AfD preservation: WDC 65C21 (CC BY-SA)

← Older revision	Revision as of 05:14, 29 September 2026
(No difference)

wikipedia>Suriname0: Nominated for redirecting; see :Wikipedia:Articles for deletion/WDC 65C21.

2026-09-18T15:38:54Z

Nominated for redirecting; see Wikipedia:Articles for deletion/WDC 65C21.

← Older revision		Revision as of 15:38, 18 September 2026
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	{{Short description\|Peripheral Interface Adapter made by Western Design Center}}		{{Short description\|Peripheral Interface Adapter made by Western Design Center}}
			<!-- Please do not remove or change this AfD message until the discussion has been closed. -->
			{{Article for deletion/dated\|page=WDC 65C21\|timestamp=20260918153854\|year=2026\|month=September\|day=18\|substed=yes\|help=off\|outcome=redirecting\|target=Western Design Center}}
			<!-- Once discussion is closed, please place on talk page: {{Old AfD multi\|page=WDC 65C21\|date=18 September 2026\|result='''keep'''}} -->
			<!-- End of AfD message, feel free to edit beyond this point -->
	{{More citations needed\|date=September 2026}}		{{More citations needed\|date=September 2026}}
	[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]		[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]

wikipedia>AnomieBOT: Dating maintenance tags: {{More citations needed}}

2026-09-16T14:00:05Z

Dating maintenance tags: {{More citations needed}}

← Older revision		Revision as of 14:00, 16 September 2026
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	{{Short description\|Peripheral Interface Adapter made by Western Design Center}}		{{Short description\|Peripheral Interface Adapter made by Western Design Center}}
	{{More citations needed\|date=September, 2026}}		{{More citations needed\|date=September 2026}}
	[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]		[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]
	The '''W65C21S''' is a Peripheral Interface Adapter (PIA) for use with WDC's 65xx and other 8-bit microprocessor families. It was produced by [[Western Design Center\|Western Design Center (WDC)]].		The '''W65C21S''' is a Peripheral Interface Adapter (PIA) for use with WDC's 65xx and other 8-bit microprocessor families. It was produced by [[Western Design Center\|Western Design Center (WDC)]].

wikipedia>Wangyunfan: Added one source and changed the template into more citations needed instead of unreferenced.

2026-09-16T11:59:36Z

Added one source and changed the template into more citations needed instead of unreferenced.

← Older revision		Revision as of 11:59, 16 September 2026
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	{{Short description\|Peripheral Interface Adapter made by Western Design Center}}		{{Short description\|Peripheral Interface Adapter made by Western Design Center}}
	{{~~Unreferenced~~\|date=~~May~~ 2026}}		{{More citations needed\|date=September, 2026}}
	[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]		[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]
	The '''W65C21S''' is a Peripheral Interface Adapter (PIA) for use with WDC's 65xx and other 8-bit microprocessor families. It was produced by [[Western Design Center\|Western Design Center (WDC)]].		The '''W65C21S''' is a Peripheral Interface Adapter (PIA) for use with WDC's 65xx and other 8-bit microprocessor families. It was produced by [[Western Design Center\|Western Design Center (WDC)]].

	The W65C21S provides programmed microprocessor control of up to two peripheral devices (Port A and Port B). Peripheral device control is accomplished through two 8-bit bidirectional [[I/O]] Ports, with individually designed Data Direction Registers. The Data Direction Registers provide selection of data flow direction (input or output) at each respective I/O Port. Data flow direction may be selected on a line-by-line basis with intermixed input and output lines within the same port. The "handshake" interrupt control feature is provided by four peripheral control lines. This capability provides enhanced control over data transfer functions between the microprocessor and peripheral devices, as well as bidirectional data transfer between W65C21S [[Peripheral Interface Adapter]]s in multiprocessor systems.		The W65C21S provides programmed microprocessor control of up to two peripheral devices (Port A and Port B). Peripheral device control is accomplished through two 8-bit bidirectional [[I/O]] Ports, with individually designed Data Direction Registers. The Data Direction Registers provide selection of data flow direction (input or output) at each respective I/O Port. Data flow direction may be selected on a line-by-line basis with intermixed input and output lines within the same port. The "handshake" interrupt control feature is provided by four peripheral control lines. This capability provides enhanced control over data transfer functions between the microprocessor and peripheral devices, as well as bidirectional data transfer between W65C21S [[Peripheral Interface Adapter]]s in multiprocessor systems.<ref>{{Cite web\|url=https://www.westerndesigncenter.com/wdc/documentation/w65c21.pdf\|date=March 18, 2024\|author=THE WESTERN DESIGN CENTER, INC.\|title=W65C21 (W65C21N and W65C21S) Peripheral Interface Adapter (PIA)}}</ref>

	The PIA interfaces to the 65xx microprocessor family with a reset line, a Φ2 clock line, a read/write line, two interrupt request lines, two register select lines, three chip select lines and an 8-bit bidirectional data bus. The PIA interfaces to the peripheral devices with four interrupt/control lines and two 8-bit bidirectional buses.		The PIA interfaces to the 65xx microprocessor family with a reset line, a Φ2 clock line, a read/write line, two interrupt request lines, two register select lines, three chip select lines and an 8-bit bidirectional data bus. The PIA interfaces to the peripheral devices with four interrupt/control lines and two 8-bit bidirectional buses.

wikipedia>Suriname0: reflist, remove promotional features section

2026-09-14T22:52:29Z

reflist, remove promotional features section

← Older revision		Revision as of 22:52, 14 September 2026
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	{{Unreferenced\|date=May 2026}}		{{Unreferenced\|date=May 2026}}
	[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]		[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]
	The '''W65C21S''' is a ~~very flexible~~ Peripheral Interface Adapter (PIA) for use with WDC's 65xx and other 8-bit microprocessor families. It is produced by [[Western Design Center\|Western Design Center (WDC)]].		The '''W65C21S''' is a Peripheral Interface Adapter (PIA) for use with WDC's 65xx and other 8-bit microprocessor families. It was produced by [[Western Design Center\|Western Design Center (WDC)]].

	The W65C21S provides programmed microprocessor control of up to two peripheral devices (Port A and Port B). Peripheral device control is accomplished through two 8-bit bidirectional [[I/O]] Ports, with individually designed Data Direction Registers. The Data Direction Registers provide selection of data flow direction (input or output) at each respective I/O Port. Data flow direction may be selected on a line-by-line basis with intermixed input and output lines within the same port. The "handshake" interrupt control feature is provided by four peripheral control lines. This capability provides enhanced control over data transfer functions between the microprocessor and peripheral devices, as well as bidirectional data transfer between W65C21S [[Peripheral Interface Adapter]]s in multiprocessor systems.		The W65C21S provides programmed microprocessor control of up to two peripheral devices (Port A and Port B). Peripheral device control is accomplished through two 8-bit bidirectional [[I/O]] Ports, with individually designed Data Direction Registers. The Data Direction Registers provide selection of data flow direction (input or output) at each respective I/O Port. Data flow direction may be selected on a line-by-line basis with intermixed input and output lines within the same port. The "handshake" interrupt control feature is provided by four peripheral control lines. This capability provides enhanced control over data transfer functions between the microprocessor and peripheral devices, as well as bidirectional data transfer between W65C21S [[Peripheral Interface Adapter]]s in multiprocessor systems.
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	The W65C21S PIA is organized into two independent sections referred to as the A Side and the B Side. Each section consists of Control Register (CRA, CRB), Data Direction Register (DDRA, DDRB), Output Register (ORA, ORB), Interrupt Status Control (ISCA, ISCB) and the buffers necessary to drive the Peripheral Interface buses. Data Bus Buffers (DBB) interface data from the two sections to the data bus, while the Date Input Register (DIR) interfaces data from the DBB to the PIA registers. Chip Select and RWB control circuitry interface to the processor bus control lines.		The W65C21S PIA is organized into two independent sections referred to as the A Side and the B Side. Each section consists of Control Register (CRA, CRB), Data Direction Register (DDRA, DDRB), Output Register (ORA, ORB), Interrupt Status Control (ISCA, ISCB) and the buffers necessary to drive the Peripheral Interface buses. Data Bus Buffers (DBB) interface data from the two sections to the data bus, while the Date Input Register (DIR) interfaces data from the DBB to the PIA registers. Chip Select and RWB control circuitry interface to the processor bus control lines.

	==~~Features of the W65C21S~~==		==References==
	*Low power [[CMOS]] N-well silicon gate technology		{{reflist}}
	High speed/Low power replacement for [[Motorola]] / [[Rockwell Automation\|Rockwell]] / [[ON Semiconductor\|AMI]] / [[MOS Technology]] / MOSTEK / [[Hitachi]] / [[ST Microelectronics]] / [[GTE]] / [[California Micro Devices\|CMD]] 6520, 6521, 6820, [[Peripheral Interface Adapter\|6821]] PIA's
	*Two 8-bit bidirectional I/O ports with individual data direction control.
	*Automatic "Handshake" control of data transfers
	*Two interrupts (one for each port) with program control
	*Static to 14 MHz operation, with high speed Port A, CA2 outputs.
	*Industrial temperature range
	*40 Pin Plastic Dip and 44 Pin Plastic PLCC versions
	*5 volt ± 10% supply requirements
	*Compatible with the [[Western Design Center\|65xx]] and [[Motorola 6800\|68xx]] family of microprocessors

	==External links==		==External links==

wikipedia>Ivtue: Added {{Unreferenced}} tag

2026-05-25T18:27:26Z

Added {{Unreferenced}} tag

← Older revision		Revision as of 18:27, 25 May 2026
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	{{Short description\|Peripheral Interface Adapter made by Western Design Center}}		{{Short description\|Peripheral Interface Adapter made by Western Design Center}}
			{{Unreferenced\|date=May 2026}}
	[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]		[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]
	The '''W65C21S''' is a very flexible Peripheral Interface Adapter (PIA) for use with WDC's 65xx and other 8-bit microprocessor families. It is produced by [[Western Design Center\|Western Design Center (WDC)]].		The '''W65C21S''' is a very flexible Peripheral Interface Adapter (PIA) for use with WDC's 65xx and other 8-bit microprocessor families. It is produced by [[Western Design Center\|Western Design Center (WDC)]].

wikipedia>Ivtue: Adding local short description: "Peripheral Interface Adapter made by Western Design Center", overriding Wikidata description "Peripheral Interface Adapter"

2026-05-25T18:27:17Z

Adding local short description: "Peripheral Interface Adapter made by Western Design Center", overriding Wikidata description "Peripheral Interface Adapter"

← Older revision		Revision as of 18:27, 25 May 2026
Line 1:		Line 1:
			{{Short description\|Peripheral Interface Adapter made by Western Design Center}}
	[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]		[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]
	The '''W65C21S''' is a very flexible Peripheral Interface Adapter (PIA) for use with WDC's 65xx and other 8-bit microprocessor families. It is produced by [[Western Design Center\|Western Design Center (WDC)]].		The '''W65C21S''' is a very flexible Peripheral Interface Adapter (PIA) for use with WDC's 65xx and other 8-bit microprocessor families. It is produced by [[Western Design Center\|Western Design Center (WDC)]].

wikipedia>Beland: convert special characters found by Wikipedia:Typo Team/moss (via WP:JWB)

2025-02-06T11:48:51Z

convert special characters found by Wikipedia:Typo Team/moss (via WP:JWB)

← Older revision		Revision as of 05:28, 29 September 2026
Line 1:		Line 1:
	~~{{Short description\|Peripheral Interface Adapter made by Western Design Center}}~~
	~~<!-- Please do not remove or change this AfD message until the discussion has been closed. -->~~
	~~{{Article for deletion/dated\|page=WDC 65C21\|timestamp=20260918153854\|year=2026\|month=September\|day=18\|substed=yes\|help=off\|outcome=redirecting\|target=Western Design Center}}~~
	~~<!-- Once discussion is closed, please place on talk page: {{Old AfD multi\|page=WDC 65C21\|date=18 September 2026\|result='''keep'''}} -->~~
	~~<!-- End of AfD message, feel free to edit beyond this point -->~~
	~~{{More citations needed\|date=September 2026}}~~
	[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]		[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]
	The '''W65C21S''' is a Peripheral Interface Adapter (PIA) for use with WDC's 65xx and other 8-bit microprocessor families. It was produced by [[Western Design Center\|Western Design Center (WDC)]].		The '''W65C21S''' is a Peripheral Interface Adapter (PIA) for use with WDC's 65xx and other 8-bit microprocessor families. It was produced by [[Western Design Center\|Western Design Center (WDC)]].

← Older revision		Revision as of 15:38, 18 September 2026
Line 1:		Line 1:
	{{Short description\|Peripheral Interface Adapter made by Western Design Center}}		{{Short description\|Peripheral Interface Adapter made by Western Design Center}}
			<!-- Please do not remove or change this AfD message until the discussion has been closed. -->
			{{Article for deletion/dated\|page=WDC 65C21\|timestamp=20260918153854\|year=2026\|month=September\|day=18\|substed=yes\|help=off\|outcome=redirecting\|target=Western Design Center}}
			<!-- Once discussion is closed, please place on talk page: {{Old AfD multi\|page=WDC 65C21\|date=18 September 2026\|result='''keep'''}} -->
			<!-- End of AfD message, feel free to edit beyond this point -->
	{{More citations needed\|date=September 2026}}		{{More citations needed\|date=September 2026}}
	[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]		[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]

← Older revision		Revision as of 14:00, 16 September 2026
Line 1:		Line 1:
	{{Short description\|Peripheral Interface Adapter made by Western Design Center}}		{{Short description\|Peripheral Interface Adapter made by Western Design Center}}
	{{More citations needed\|date=September, 2026}}		{{More citations needed\|date=September 2026}}
	[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]		[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]
	The '''W65C21S''' is a Peripheral Interface Adapter (PIA) for use with WDC's 65xx and other 8-bit microprocessor families. It was produced by [[Western Design Center\|Western Design Center (WDC)]].		The '''W65C21S''' is a Peripheral Interface Adapter (PIA) for use with WDC's 65xx and other 8-bit microprocessor families. It was produced by [[Western Design Center\|Western Design Center (WDC)]].

← Older revision		Revision as of 11:59, 16 September 2026
Line 1:		Line 1:
	{{Short description\|Peripheral Interface Adapter made by Western Design Center}}		{{Short description\|Peripheral Interface Adapter made by Western Design Center}}
	{{~~Unreferenced~~\|date=~~May~~ 2026}}		{{More citations needed\|date=September, 2026}}
	[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]		[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]
	The '''W65C21S''' is a Peripheral Interface Adapter (PIA) for use with WDC's 65xx and other 8-bit microprocessor families. It was produced by [[Western Design Center\|Western Design Center (WDC)]].		The '''W65C21S''' is a Peripheral Interface Adapter (PIA) for use with WDC's 65xx and other 8-bit microprocessor families. It was produced by [[Western Design Center\|Western Design Center (WDC)]].

	The W65C21S provides programmed microprocessor control of up to two peripheral devices (Port A and Port B). Peripheral device control is accomplished through two 8-bit bidirectional [[I/O]] Ports, with individually designed Data Direction Registers. The Data Direction Registers provide selection of data flow direction (input or output) at each respective I/O Port. Data flow direction may be selected on a line-by-line basis with intermixed input and output lines within the same port. The "handshake" interrupt control feature is provided by four peripheral control lines. This capability provides enhanced control over data transfer functions between the microprocessor and peripheral devices, as well as bidirectional data transfer between W65C21S [[Peripheral Interface Adapter]]s in multiprocessor systems.		The W65C21S provides programmed microprocessor control of up to two peripheral devices (Port A and Port B). Peripheral device control is accomplished through two 8-bit bidirectional [[I/O]] Ports, with individually designed Data Direction Registers. The Data Direction Registers provide selection of data flow direction (input or output) at each respective I/O Port. Data flow direction may be selected on a line-by-line basis with intermixed input and output lines within the same port. The "handshake" interrupt control feature is provided by four peripheral control lines. This capability provides enhanced control over data transfer functions between the microprocessor and peripheral devices, as well as bidirectional data transfer between W65C21S [[Peripheral Interface Adapter]]s in multiprocessor systems.<ref>{{Cite web\|url=https://www.westerndesigncenter.com/wdc/documentation/w65c21.pdf\|date=March 18, 2024\|author=THE WESTERN DESIGN CENTER, INC.\|title=W65C21 (W65C21N and W65C21S) Peripheral Interface Adapter (PIA)}}</ref>

	The PIA interfaces to the 65xx microprocessor family with a reset line, a Φ2 clock line, a read/write line, two interrupt request lines, two register select lines, three chip select lines and an 8-bit bidirectional data bus. The PIA interfaces to the peripheral devices with four interrupt/control lines and two 8-bit bidirectional buses.		The PIA interfaces to the 65xx microprocessor family with a reset line, a Φ2 clock line, a read/write line, two interrupt request lines, two register select lines, three chip select lines and an 8-bit bidirectional data bus. The PIA interfaces to the peripheral devices with four interrupt/control lines and two 8-bit bidirectional buses.

← Older revision		Revision as of 18:27, 25 May 2026
Line 1:		Line 1:
	{{Short description\|Peripheral Interface Adapter made by Western Design Center}}		{{Short description\|Peripheral Interface Adapter made by Western Design Center}}
			{{Unreferenced\|date=May 2026}}
	[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]		[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]
	The '''W65C21S''' is a very flexible Peripheral Interface Adapter (PIA) for use with WDC's 65xx and other 8-bit microprocessor families. It is produced by [[Western Design Center\|Western Design Center (WDC)]].		The '''W65C21S''' is a very flexible Peripheral Interface Adapter (PIA) for use with WDC's 65xx and other 8-bit microprocessor families. It is produced by [[Western Design Center\|Western Design Center (WDC)]].

← Older revision		Revision as of 11:48, 6 February 2025
Line 1:		Line 1:
	[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]		[[Image:W65C21S6TPG-14 lg.jpg\|thumb\|WDC W65C21S Peripheral Interface Adapter (PIA)]]
	The '''W65C21S''' is a very flexible Peripheral Interface Adapter (PIA) for use with ~~WDC’s~~ 65xx and other 8-bit microprocessor families. It is produced by [[Western Design Center\|Western Design Center (WDC)]].		The '''W65C21S''' is a very flexible Peripheral Interface Adapter (PIA) for use with WDC's 65xx and other 8-bit microprocessor families. It is produced by [[Western Design Center\|Western Design Center (WDC)]].

	The W65C21S provides programmed microprocessor control of up to two peripheral devices (Port A and Port B). Peripheral device control is accomplished through two 8-bit bidirectional [[I/O]] Ports, with individually designed Data Direction Registers. The Data Direction Registers provide selection of data flow direction (input or output) at each respective I/O Port. Data flow direction may be selected on a line-by-line basis with intermixed input and output lines within the same port. The ~~“handshake”~~ interrupt control feature is provided by four peripheral control lines. This capability provides enhanced control over data transfer functions between the microprocessor and peripheral devices, as well as bidirectional data transfer between W65C21S [[Peripheral Interface Adapter]]s in multiprocessor systems.		The W65C21S provides programmed microprocessor control of up to two peripheral devices (Port A and Port B). Peripheral device control is accomplished through two 8-bit bidirectional [[I/O]] Ports, with individually designed Data Direction Registers. The Data Direction Registers provide selection of data flow direction (input or output) at each respective I/O Port. Data flow direction may be selected on a line-by-line basis with intermixed input and output lines within the same port. The "handshake" interrupt control feature is provided by four peripheral control lines. This capability provides enhanced control over data transfer functions between the microprocessor and peripheral devices, as well as bidirectional data transfer between W65C21S [[Peripheral Interface Adapter]]s in multiprocessor systems.

	The PIA interfaces to the 65xx microprocessor family with a reset line, a ϕ2 clock line, a read/write line, two interrupt request lines, two register select lines, three chip select lines and an 8-bit bidirectional data bus. The PIA interfaces to the peripheral devices with four interrupt/control lines and two 8-bit bidirectional buses.		The PIA interfaces to the 65xx microprocessor family with a reset line, a Φ2 clock line, a read/write line, two interrupt request lines, two register select lines, three chip select lines and an 8-bit bidirectional data bus. The PIA interfaces to the peripheral devices with four interrupt/control lines and two 8-bit bidirectional buses.

	The W65C21S PIA is organized into two independent sections referred to as the A Side and the B Side. Each section consists of Control Register (CRA, CRB), Data Direction Register (DDRA, DDRB), Output Register (ORA, ORB), Interrupt Status Control (ISCA, ISCB) and the buffers necessary to drive the Peripheral Interface buses. Data Bus Buffers (DBB) interface data from the two sections to the data bus, while the Date Input Register (DIR) interfaces data from the DBB to the PIA registers. Chip Select and RWB control circuitry interface to the processor bus control lines.		The W65C21S PIA is organized into two independent sections referred to as the A Side and the B Side. Each section consists of Control Register (CRA, CRB), Data Direction Register (DDRA, DDRB), Output Register (ORA, ORB), Interrupt Status Control (ISCA, ISCB) and the buffers necessary to drive the Peripheral Interface buses. Data Bus Buffers (DBB) interface data from the two sections to the data bus, while the Date Input Register (DIR) interfaces data from the DBB to the PIA registers. Chip Select and RWB control circuitry interface to the processor bus control lines.
Line 10:		Line 10:
	==Features of the W65C21S==		==Features of the W65C21S==
	*Low power [[CMOS]] N-well silicon gate technology		*Low power [[CMOS]] N-well silicon gate technology
	High speed/Low power replacement for [[Motorola]] / [[Rockwell Automation\|Rockwell]] / [[ON Semiconductor\|AMI]] / [[MOS Technology]] / MOSTEK / [[Hitachi]] / [[ST Microelectronics]] / [[GTE]] / [[California Micro Devices\|CMD]] 6520, 6521, 6820, [[Peripheral Interface Adapter\|6821]] ~~PIA’s~~		High speed/Low power replacement for [[Motorola]] / [[Rockwell Automation\|Rockwell]] / [[ON Semiconductor\|AMI]] / [[MOS Technology]] / MOSTEK / [[Hitachi]] / [[ST Microelectronics]] / [[GTE]] / [[California Micro Devices\|CMD]] 6520, 6521, 6820, [[Peripheral Interface Adapter\|6821]] PIA's
	*Two 8-bit bidirectional I/O ports with individual data direction control.		*Two 8-bit bidirectional I/O ports with individual data direction control.
	*Automatic ~~“Handshake”~~ control of data transfers		*Automatic "Handshake" control of data transfers
	*Two interrupts (one for each port) with program control		*Two interrupts (one for each port) with program control
	*Static to 14 MHz operation, with high speed Port A, CA2 outputs.		*Static to 14 MHz operation, with high speed Port A, CA2 outputs.