8251 USART chip - Revision history

Bryce at 10:50, 14 November 2011

2011-11-14T10:50:38Z

← Older revision		Revision as of 10:50, 14 November 2011
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	The original '''8251''' seems to be very rare (there's no programming info found in the internet). The '''8251A''' is backwards compatible, but includes some additional features. The 8251A gives some details on the additional features, so one could eventually use the '''8251A''' datasheet to reconstruct the functionality of the original '''8251'''.		The original '''8251''' seems to be very rare (there's no programming info found in the internet). The '''8251A''' is backwards compatible, but includes some additional features. The 8251A gives some details on the additional features, so one could eventually use the '''8251A''' datasheet to reconstruct the functionality of the original '''8251'''.

	However, since the 8251 is so rare, it's rather ~~doubtworthy~~ that the Aleste or Circit actually uses ~~that~~ chips, probably ~~they~~ use 8251A chips.		However, since the 8251 is so rare, it's rather doubtful that the Aleste or Circit actually uses these chips, they probably use 8251A chips.

	* The Circit advert says 8251 (which is maybe meant to be an abbreviation for 8251A).		* The Circit advert says 8251 (which is maybe meant to be an abbreviation for 8251A).
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	* [[Media:8251A.pdf]] - newer 8251A datasheet (detailed info)		* [[Media:8251A.pdf]] - newer 8251A datasheet (detailed info)
	* [[Media:8251.pdf]] - older 8251 datasheet (pin-~~outs~~ only, without programming info)		* [[Media:8251.pdf]] - older 8251 datasheet (pin-out only, without programming info)

	[[Category:Electronic Component]]		[[Category:Electronic Component]]

MacDeath at 23:40, 16 December 2010

2010-12-16T23:40:56Z

← Older revision		Revision as of 23:40, 16 December 2010
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	* [[Media:8251A.pdf]] - newer 8251A datasheet (detailed info)		* [[Media:8251A.pdf]] - newer 8251A datasheet (detailed info)
	* [[Media:8251.pdf]] - older 8251 datasheet (pin-outs only, without programming info)		* [[Media:8251.pdf]] - older 8251 datasheet (pin-outs only, without programming info)

			[[Category:Electronic Component]]

Nocash: /* Schneiderware V/24 Interface */

2010-10-01T06:40:17Z

Schneiderware V/24 Interface

← Older revision		Revision as of 06:40, 1 October 2010
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	F9E1h (or F9E3h) Schneiderware V/24 8251 USART chip Control		F9E1h (or F9E3h) Schneiderware V/24 8251 USART chip Control
	Clock source comes from a [[8253 chip]].		Clock source comes from a [[8253 chip]].
	Clock input to that chip is jumper-selectable: 2MHz (default), or 1MHz		Clock input to that chip is jumper-selectable: 2MHz (default), or 1MHz.
			Caution: The RTS/CTS and DSR/DTR handshaking signals are disabled by
			default (via jumpers) (and, in worst case, also by additional inaccesible
			hardwired connections, hidden underneath of the jumpers)

	----		----

Nocash at 13:55, 30 September 2010

2010-09-30T13:55:40Z

@@ Line 1: / Line 1: @@
 == Registers ==
@@ Line 66: / Line 41: @@
    Bit  Expl.
 -7  Data
 == 8251 vs 8251A ==

Nocash: /* Cirkit Serial Interface */

2010-09-03T22:47:50Z

Cirkit Serial Interface

← Older revision		Revision as of 22:47, 3 September 2010
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	FADFh - Cirkit - 8251 UART Data register		FADFh - Cirkit - 8251 UART Data register
	FBDFh - Cirkit - 8251 UART Status/Control register		FBDFh - Cirkit - 8251 UART Status/Control register
	TX clock source is fixed (19.2KHz), RX clock source can be selected via DTR bit (1200Hz or 19.2KHz).		TX clock source is fixed (19.2KHz), RX clock source can be selected via DTR bit (1200Hz or 19.2KHz).

	== Registers ==		== Registers ==

Nocash: /* Cirkir Serial Interface */

2010-09-03T22:47:23Z

Cirkir Serial Interface

← Older revision		Revision as of 22:47, 3 September 2010
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	----		----

	=== ~~Cirkir~~ Serial Interface ===		=== Cirkit Serial Interface ===
	Used by [[Cirkit serial interface]] (for use with the included Prestel Link modem)):		Used by [[Cirkit serial interface]] (for use with the included Prestel Link modem)):
	FADFh - Cirkit - 8251 UART Data register		FADFh - Cirkit - 8251 UART Data register

Nocash at 22:46, 3 September 2010

2010-09-03T22:46:59Z

← Older revision		Revision as of 22:46, 3 September 2010
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	== Usage in CPCs ==		== Usage in CPCs ==

	Used by [[Aleste 520EX]]:		=== Aleste 520EX ===
	EEXXh Aleste 8251 USART chip (RS232/Mouse) Data (R/W)		Used by [[Aleste 520EX]] (a CPC clone with built-in RS232 interface):
	EFXXh Aleste 8251 USART chip (RS232/Mouse) Control/Status (R/W)		EEXXh Aleste - 8251 USART chip (RS232/Mouse) Data (R/W)
			EFXXh Aleste - 8251 USART chip (RS232/Mouse) Control/Status (R/W)
	Uses a KR580WW51A (russian clone of the 8251).		Uses a KR580WW51A (russian clone of the 8251).
	Clock source comes from a [[8253 chip]].		Clock source comes from a [[8253 chip]].

	----		----

			=== MHT Ingenieros RS232 para Amstrad ===
			Used by RS-232 para Amstrad from MHT Ingenieros, mapped to Ports:
			FADCh - MHT RS232 - 8251 USART data
			FADDh - MHT RS232 - 8251 USART control/status
			Clock source comes from a [[8253 chip]].

			----

			=== Cirkir Serial Interface ===
	Used by [[Cirkit serial interface]] (for use with the included Prestel Link modem)):		Used by [[Cirkit serial interface]] (for use with the included Prestel Link modem)):
	FADFh - Cirkit 8251 UART Data register		FADFh - Cirkit - 8251 UART Data register
	FBDFh - Cirkit 8251 UART Status/Control register		FBDFh - Cirkit - 8251 UART Status/Control register
	TX clock source is fixed (19.2KHz), RX clock source can be selected via DTR bit (1200Hz or 19.2KHz).		TX clock source is fixed (19.2KHz), RX clock source can be selected via DTR bit (1200Hz or 19.2KHz).

Nocash: /* Registers */

2010-08-05T12:23:21Z

Registers

← Older revision		Revision as of 12:23, 5 August 2010
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	=== Control Register (W) ===		=== Control Register (W) ===
	The first write after internal or external Reset is the "Mode Instruction":		The first write after internal or external Reset is the "Mode Instruction":
			Bit Expl.
	0-1 Baud Rate Divider (0=Sync Mode, 1=Div1, 2=Div16, 3=Div64)		0-1 Baud Rate Divider (0=Sync Mode, 1=Div1, 2=Div16, 3=Div64)
	2-3 Character Length (0=5bit, 1=6bit, 2=7bit, 3=8bit)		2-3 Character Length (0=5bit, 1=6bit, 2=7bit, 3=8bit)
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	3rd write - Sync Character 2		3rd write - Sync Character 2
	All further writes to the Control Register are "Command Instructions":		All further writes to the Control Register are "Command Instructions":
			Bit Expl.
	0 Transmit Enable (0=Disable, 1=Enable)		0 Transmit Enable (0=Disable, 1=Enable)
	1 Data Terminal Ready (0=No, 1=Yes) (DTR Pin)		1 Data Terminal Ready (0=No, 1=Yes) (DTR Pin)
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	=== Status Register (R) ===		=== Status Register (R) ===
			Bit Expl.
	0 Transmit Ready (0=Busy, 1=Ready; "DB Buffer Empty")		0 Transmit Ready (0=Busy, 1=Ready; "DB Buffer Empty")
	1 Receive Ready		1 Receive Ready
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	=== Data Register (R/W) ===		=== Data Register (R/W) ===
			Bit Expl.
	0-7 Data		0-7 Data


	== 8251 vs 8251A ==		== 8251 vs 8251A ==

Nocash: /* Usage in CPCs */

2010-08-05T12:18:17Z

Usage in CPCs

← Older revision		Revision as of 12:18, 5 August 2010
Line 8:		Line 8:

	----		----
			Used by [[Cirkit serial interface]] (for use with the included Prestel Link modem)):
	Used by [[Cirkit serial interface]]:		FADFh - Cirkit 8251 UART Data register
	~~Clock~~ source ~~and I/O Ports are unknown~~.		FBDFh - Cirkit 8251 UART Status/Control register
			TX clock source is fixed (19.2KHz), RX clock source can be selected via DTR bit (1200Hz or 19.2KHz).

	== Registers ==		== Registers ==

Nocash at 14:18, 22 February 2010

2010-02-22T14:18:17Z

@@ Line 1: / Line 1: @@
-* A KR580WW51A (russian clone of the 8251) is used by [[Aleste 520EX]], clock source comes from a [[8253 chip]].
+== Usage in CPCs ==
-* A 8251 is said to be used by [[Cirkit serial interface]], clock source and I/O ports are unknown.
 == 8251 vs 8251A ==