Apple Desktop Bus - Revision history

Josh: Fix two red links: point the Macintosh Portable mention at the hosted service manual, and unlink the non-existent Universal Serial Bus page

2026-09-27T07:46:42Z

Fix two red links: point the Macintosh Portable mention at the hosted service manual, and unlink the non-existent Universal Serial Bus page

← Older revision		Revision as of 08:46, 27 September 2026
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	\| manufacturer = Apple Computer		\| manufacturer = Apple Computer
	\| production = 1986-1999		\| production = 1986-1999
	\| superseded = ~~[[Universal Serial Bus\|~~USB]]		\| superseded = USB
	\| external = Yes		\| external = Yes
	\| hotplug = No - Apple's documentation warns against it		\| hotplug = No - Apple's documentation warns against it
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	The '''Apple Desktop Bus''' ('''ADB''') is Apple's single-master, multislave bit-serial bus for low-speed input devices — keyboards, mice, graphics tablets and the like. Apple describes it as connecting "up to 16 low-speed input devices".<ref name="gmfh">''Guide to the Macintosh Family Hardware'', second edition, Apple Computer, Inc. / Addison-Wesley, 1990 — hosted on this wiki as [[:File:Apple Guide to the Macintosh Family Hardware 2nd Edition 1990.pdf]]. Chapter 8, "Apple Desktop Bus", pages 287–326: bus overview (single-master multislave, up to 16 devices, ADB transceiver IC described as a 4-bit microcontroller, two connectors wired in parallel, four-conductor shielded cable, the warning against unplugging a device while the computer is running, the 500 mA total bus limit, the 5 m cable length and 100 pF/m capacitance limits, and the note that daisy-chaining more than three devices on one port is not recommended); Table 8-1 connector signal assignments; Table 8-2 transceiver electrical characteristics; Table 8-4 register 0 in the Apple Standard Mouse and the accompanying note on 100 ±10 and 200 ±10 counts per inch; Tables 8-7 and 8-8 registers 0 and 2 in the Apple Standard Keyboard; Tables 8-10 and 8-11 registers 0 and 2 in the Apple Extended Keyboard; Table 8-12 transaction states; Table 8-13 command byte syntax; Table 8-14 the full timing specification; Table 8-15 device register 3; Table 8-16 device addresses; Table 8-17 reserved Device Handler IDs; the collision-detection, polling (11 ms) and error-condition sections. Chapter 9, "Floppy Disk Interfaces", is the source for the floppy-drive material.</ref> It was introduced on the [[Apple IIGS]] in September 1986 and carried across the Macintosh line from the [[Macintosh SE]] and [[Macintosh II]] in 1987 until USB replaced it at the end of the 1990s.		The '''Apple Desktop Bus''' ('''ADB''') is Apple's single-master, multislave bit-serial bus for low-speed input devices — keyboards, mice, graphics tablets and the like. Apple describes it as connecting "up to 16 low-speed input devices".<ref name="gmfh">''Guide to the Macintosh Family Hardware'', second edition, Apple Computer, Inc. / Addison-Wesley, 1990 — hosted on this wiki as [[:File:Apple Guide to the Macintosh Family Hardware 2nd Edition 1990.pdf]]. Chapter 8, "Apple Desktop Bus", pages 287–326: bus overview (single-master multislave, up to 16 devices, ADB transceiver IC described as a 4-bit microcontroller, two connectors wired in parallel, four-conductor shielded cable, the warning against unplugging a device while the computer is running, the 500 mA total bus limit, the 5 m cable length and 100 pF/m capacitance limits, and the note that daisy-chaining more than three devices on one port is not recommended); Table 8-1 connector signal assignments; Table 8-2 transceiver electrical characteristics; Table 8-4 register 0 in the Apple Standard Mouse and the accompanying note on 100 ±10 and 200 ±10 counts per inch; Tables 8-7 and 8-8 registers 0 and 2 in the Apple Standard Keyboard; Tables 8-10 and 8-11 registers 0 and 2 in the Apple Extended Keyboard; Table 8-12 transaction states; Table 8-13 command byte syntax; Table 8-14 the full timing specification; Table 8-15 device register 3; Table 8-16 device addresses; Table 8-17 reserved Device Handler IDs; the collision-detection, polling (11 ms) and error-condition sections. Chapter 9, "Floppy Disk Interfaces", is the source for the floppy-drive material.</ref> It was introduced on the [[Apple IIGS]] in September 1986 and carried across the Macintosh line from the [[Macintosh SE]] and [[Macintosh II]] in 1987 until USB replaced it at the end of the 1990s.

	On most Macintosh models the bus hardware is three things: an '''ADB transceiver IC''' — which Apple describes as a 4-bit microcontroller — that drives the bus and reads device status; the '''VIA''', which is how the CPU talks to the transceiver; and '''two 4-pin ADB connectors wired in parallel''' on the rear panel. The [[Macintosh Portable]] is the exception: there the Power Manager IC performs the transceiver function, and the Macintosh IIfx uses the IOP custom IC instead.<ref name="gmfh" />		On most Macintosh models the bus hardware is three things: an '''ADB transceiver IC''' — which Apple describes as a 4-bit microcontroller — that drives the bus and reads device status; the '''VIA''', which is how the CPU talks to the transceiver; and '''two 4-pin ADB connectors wired in parallel''' on the rear panel. The [[Macintosh Portable Service Source\|Macintosh Portable]] is the exception: there the Power Manager IC performs the transceiver function, and the Macintosh IIfx uses the IOP custom IC instead.<ref name="gmfh" />

	== Physical Interface ==		== Physical Interface ==

Josh: Retarget link to the kept page title after the duplicate-title pair was resolved

2026-09-27T07:39:36Z

Retarget link to the kept page title after the duplicate-title pair was resolved

← Older revision		Revision as of 08:39, 27 September 2026
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	For the programming side of AppleTalk rather than the wiring, see		For the programming side of AppleTalk rather than the wiring, see
	[[Programming ~~With~~ AppleTalk 1991]]; it contains no electrical data.		[[Programming with AppleTalk 1991]]; it contains no electrical data.

	== See Also ==		== See Also ==

Josh: P4 verification: cite Apple's own AppleTalk bus-termination material from the hosted Technical Procedures binder, and distinguish it from ADB

2026-09-25T07:54:15Z

P4 verification: cite Apple's own AppleTalk bus-termination material from the hosted Technical Procedures binder, and distinguish it from ADB

← Older revision		Revision as of 08:54, 25 September 2026
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	ADB-to-USB conversion is the usual route to using these devices today. Commercial adapters of the period (notably Griffin's iMate) are long discontinued, and community-built converters come and go. This page does not endorse a particular one; check current sources before buying, and check that whatever you find implements the timing in the table above rather than approximating it.		ADB-to-USB conversion is the usual route to using these devices today. Commercial adapters of the period (notably Griffin's iMate) are long discontinued, and community-built converters come and go. This page does not endorse a particular one; check current sources before buying, and check that whatever you find implements the timing in the table above rather than approximating it.

			== Not to be confused with AppleTalk ==

			ADB and AppleTalk are different buses with different failure modes, and the wiki holds Apple's own
			material on the AppleTalk side. Apple's '''Macintosh Office (AppleTalk) Technical Procedures''',
			bound into the binder described at
			[[Service Support Tranning Programs Laserwriter Technical Procedures Jan 1985]], troubleshoots a
			LocalTalk network by flowchart — ONE NODE, TWO OR MORE BUT NOT ALL, ALL NODES, FIRST NODE and
			RARE CASE — and its appendix explains '''bus termination problems''', why '''noisy nodes''' break
			the bus, cable impedance, '''dangling cables''' and '''circular networks'''. Apple notes there that
			the AppleTalk bus conforms to the EIA electrical interface specification.<ref name="lwtp85">Apple Computer, ''Apple LaserWriter Printer Technical Procedures'', preliminary version for internal use only, sections stamped rev. Jan 85 and rev. Feb 85. Held on this wiki inside the Service Support Training Programs binder scan, described at [[Service Support Tranning Programs Laserwriter Technical Procedures Jan 1985]] ([[:File:Service_Support_Tranning_Programs_Laserwriter_Technical_Procedures_Jan_1985.pdf]]).</ref>

			For the programming side of AppleTalk rather than the wiring, see
			[[Programming With AppleTalk 1991]]; it contains no electrical data.

	== See Also ==		== See Also ==

Josh: Rebuild from Guide to the Macintosh Family Hardware ch.8 (now hosted): corrected pin 2 to POWER.ON, Sync 65us/stop 70us, ~10 kbit/s not 125; replaced fabricated handler-ID registry, device-address table and 6-command table with Apple Tables 8-16/8-17/8-13; added Tables 8-2, 8-12, 8-14, 8-15, keyboard registers 0/2; 11 ms polling; removed invented electrical specs, patent list and troubleshooting table

2026-09-23T18:00:51Z

Rebuild from Guide to the Macintosh Family Hardware ch.8 (now hosted): corrected pin 2 to POWER.ON, Sync 65us/stop 70us, ~10 kbit/s not 125; replaced fabricated handler-ID registry, device-address table and 6-command table with Apple Tables 8-16/8-17/8-13; added Tables 8-2, 8-12, 8-14, 8-15, keyboard registers 0/2; 11 ms polling; removed invented electrical specs, patent list and troubleshooting table

Show changes

Josh at 14:17, 6 September 2025

2025-09-06T14:17:35Z

← Older revision		Revision as of 15:17, 6 September 2025
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	\| style = Serial		\| style = Serial
	\| pinout_caption = ADB connector (female socket)		\| pinout_caption = ADB connector (female socket)
	}}		\|pinout=[[File:Apple Desktop Bus Connector Pinout.png\|150px]]}}
	'''Apple Desktop Bus''' ('''ADB''') is a proprietary bit-serial peripheral bus connecting low-speed input devices to computers. Designed by Steve Wozniak and introduced on the [[Apple IIGS]] in September 1986, ADB was created to provide a simple, low-cost method for connecting keyboards, mice, and other input devices in a daisy-chain configuration without requiring hubs. The technology was quickly adopted for the Macintosh line beginning with the [[Macintosh SE]] and [[Macintosh II]] in March 1987, and remained Apple's standard peripheral interface until its replacement by [[USB]] in 1998-1999.		'''Apple Desktop Bus''' ('''ADB''') is a proprietary bit-serial peripheral bus connecting low-speed input devices to computers. Designed by Steve Wozniak and introduced on the [[Apple IIGS]] in September 1986, ADB was created to provide a simple, low-cost method for connecting keyboards, mice, and other input devices in a daisy-chain configuration without requiring hubs. The technology was quickly adopted for the Macintosh line beginning with the [[Macintosh SE]] and [[Macintosh II]] in March 1987, and remained Apple's standard peripheral interface until its replacement by [[USB]] in 1998-1999.

Josh at 14:13, 6 September 2025

2025-09-06T14:13:58Z

← Older revision		Revision as of 15:13, 6 September 2025
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	\| pinout_caption = ADB connector (female socket)		\| pinout_caption = ADB connector (female socket)
	}}		}}
	'''Apple Desktop Bus''' ('''ADB''') is a proprietary bit-serial peripheral bus connecting low-speed input devices to computers. Designed by Steve Wozniak and introduced on the [[Apple IIGS]] in September 1986, ADB was created to provide a simple, low-cost method for connecting keyboards, mice, and other input devices in a daisy-chain configuration without requiring hubs. The technology was quickly adopted for the [[Macintosh]] line beginning with the [[Macintosh SE]] and [[Macintosh II]] in March 1987, and remained Apple's standard peripheral interface until its replacement by [[USB]] in 1998-1999.		'''Apple Desktop Bus''' ('''ADB''') is a proprietary bit-serial peripheral bus connecting low-speed input devices to computers. Designed by Steve Wozniak and introduced on the [[Apple IIGS]] in September 1986, ADB was created to provide a simple, low-cost method for connecting keyboards, mice, and other input devices in a daisy-chain configuration without requiring hubs. The technology was quickly adopted for the Macintosh line beginning with the [[Macintosh SE]] and [[Macintosh II]] in March 1987, and remained Apple's standard peripheral interface until its replacement by [[USB]] in 1998-1999.

	== History and Development ==		== History and Development ==
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	=== ADB to USB Adapters ===		=== ADB to USB Adapters ===
	* '''Griffin iMate::''' Original commercial adapter (discontinued)		* '''Griffin iMate:''' Original commercial adapter (discontinued)
	* '''Wombat::''' Modern bidirectional ADB-USB converter		* '''Wombat:''' Modern bidirectional ADB-USB converter
	* '''Belkin F5U118::''' Simple ADB to USB adapter		* '''Belkin F5U118:''' Simple ADB to USB adapter

	=== USB to ADB Adapters ===		=== USB to ADB Adapters ===
	* '''Wombat::''' Allows USB devices on ADB Macs		* '''Wombat:''' Allows USB devices on ADB Macs
	* '''DIY solutions::''' Arduino-based converters		* '''DIY solutions:''' Arduino-based converters

	=== Replacement Controllers ===		=== Replacement Controllers ===
	* '''PIC16F87/88::''' Drop-in replacement for failed SE controllers		* '''PIC16F87/88:''' Drop-in replacement for failed SE controllers
	* '''Custom ASICs::''' Modern reproductions for restoration		* '''Custom ASICs:''' Modern reproductions for restoration

	== Legacy and Impact ==		== Legacy and Impact ==
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	=== Diagnostic Tools ===		=== Diagnostic Tools ===
	* '''ADB Parser::''' Classic Mac OS tool for bus analysis		* '''ADB Parser:''' Classic Mac OS tool for bus analysis
	* '''TechTool::''' Hardware diagnostic suite		* '''TechTool:''' Hardware diagnostic suite
	* '''MacsBug::''' Low-level debugging access to ADB		* '''MacsBug:''' Low-level debugging access to ADB
	[[Category:Apple Desktop Bus]]		[[Category:Apple Desktop Bus]]
	[[Category:Apple Vintage Computers]]		[[Category:Apple Vintage Computers]]
	[[Category:Apple Vintage Accessories]]		[[Category:Apple Vintage Accessories]]

Josh at 14:11, 6 September 2025

2025-09-06T14:11:00Z

Show changes

Josh at 13:28, 6 September 2025

2025-09-06T13:28:07Z

← Older revision		Revision as of 14:28, 6 September 2025
Line 21:		Line 21:
	\| pinout_caption = ADB connector (female socket)		\| pinout_caption = ADB connector (female socket)
	}}		}}

	'''Apple Desktop Bus''' ('''ADB''') is a proprietary bit-serial peripheral bus connecting low-speed input devices to computers. Designed by Steve Wozniak and introduced on the [[Apple IIGS]] in September 1986, ADB was created to provide a simple, low-cost method for connecting keyboards, mice, and other input devices in a daisy-chain configuration without requiring hubs. The technology was quickly adopted for the [[Macintosh]] line beginning with the [[Macintosh SE]] and [[Macintosh II]] in March 1987, and remained Apple's standard peripheral interface until its replacement by [[USB]] in 1998-1999.		'''Apple Desktop Bus''' ('''ADB''') is a proprietary bit-serial peripheral bus connecting low-speed input devices to computers. Designed by Steve Wozniak and introduced on the [[Apple IIGS]] in September 1986, ADB was created to provide a simple, low-cost method for connecting keyboards, mice, and other input devices in a daisy-chain configuration without requiring hubs. The technology was quickly adopted for the [[Macintosh]] line beginning with the [[Macintosh SE]] and [[Macintosh II]] in March 1987, and remained Apple's standard peripheral interface until its replacement by [[USB]] in 1998-1999.

Josh at 13:25, 6 September 2025

2025-09-06T13:25:42Z

← Older revision		Revision as of 14:25, 6 September 2025
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	{{Infobox connector		{{Infobox connector
	\| name = Apple Desktop Bus		\| name = Apple Desktop Bus
	\| logo = [[File:~~ADB_logo~~.svg\|150px]]		\| logo = [[File:Apple Desktop Bus (icon).svg\|150px]]
	\| type = Computer peripheral interface		\| type = Computer peripheral interface
	\| designer = Steve Wozniak		\| designer = Steve Wozniak

Josh at 13:24, 6 September 2025

2025-09-06T13:24:53Z

← Older revision		Revision as of 14:24, 6 September 2025
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	\| logo = [[File:ADB_logo.svg\|150px]]		\| logo = [[File:ADB_logo.svg\|150px]]
	\| type = Computer peripheral interface		\| type = Computer peripheral interface
	\| designer = [[Steve Wozniak]]		\| designer = Steve Wozniak
	\| design_date = 1985-1986		\| design_date = 1985-1986
	\| manufacturer = [[Apple Computer]]		\| manufacturer = Apple Computer
	\| production = 1986-1999		\| production = 1986-1999
	\| superseded = [[Universal Serial Bus\|USB]]		\| superseded = [[Universal Serial Bus\|USB]]
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	}}		}}

	'''Apple Desktop Bus''' ('''ADB''') is a proprietary bit-serial peripheral bus connecting low-speed input devices to computers. Designed by [[Steve Wozniak]] and introduced on the [[Apple IIGS]] in September 1986, ADB was created to provide a simple, low-cost method for connecting keyboards, mice, and other input devices in a daisy-chain configuration without requiring hubs. The technology was quickly adopted for the [[Macintosh]] line beginning with the [[Macintosh SE]] and [[Macintosh II]] in March 1987, and remained Apple's standard peripheral interface until its replacement by [[USB]] in 1998-1999.		'''Apple Desktop Bus''' ('''ADB''') is a proprietary bit-serial peripheral bus connecting low-speed input devices to computers. Designed by Steve Wozniak and introduced on the [[Apple IIGS]] in September 1986, ADB was created to provide a simple, low-cost method for connecting keyboards, mice, and other input devices in a daisy-chain configuration without requiring hubs. The technology was quickly adopted for the [[Macintosh]] line beginning with the [[Macintosh SE]] and [[Macintosh II]] in March 1987, and remained Apple's standard peripheral interface until its replacement by [[USB]] in 1998-1999.

	== History and Development ==		== History and Development ==
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	* '''1987-1998:''' Standard on all desktop Macintosh computers		* '''1987-1998:''' Standard on all desktop Macintosh computers
	* '''1991-1998:''' Used in PowerBook line		* '''1991-1998:''' Used in PowerBook line
	* '''1989-1996:''' Implemented in some [[NeXT]] computer models		* '''1989-1996:''' Implemented in some NeXT computer models
	* '''1998:''' Phased out with introduction of [[iMac]] G3 (USB-based)		* '''1998:''' Phased out with introduction of [[iMac G3]] (USB-based)
	* '''1999:''' Last external ADB port on [[Power Macintosh G3 (Blue and White)]]		* '''1999:''' Last external ADB port on [[Power Macintosh G3 (Blue and White)]]
	* '''2000-2005:''' Internal ADB protocol continued in some PowerBooks for built-in keyboards/trackpads		* '''2000-2005:''' Internal ADB protocol continued in some PowerBooks for built-in keyboards/trackpads
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	* '''TechTool::''' Hardware diagnostic suite		* '''TechTool::''' Hardware diagnostic suite
	* '''MacsBug::''' Low-level debugging access to ADB		* '''MacsBug::''' Low-level debugging access to ADB

	~~[[Category:Vintage Apple Computers]]~~
	~~[[Categroy:Apple Vintage Accessories]]~~
	[[Category:Apple Desktop Bus]]		[[Category:Apple Desktop Bus]]
			[[Category:Apple Vintage Computers]]
			[[Category:Apple Vintage Accessories]]