Apple Desktop Bus Mouse II: Difference between revisions
Rebuild from Deskthority + Guide to the Macintosh Family Hardware ch.8. TWO documented internal variants (Logitech, one screw, two boards; Mitsumi, two screws, one board), not four; no M2707 PowerBook Gray model is documented. Deleted unsourced US$89 price, dimensions, 140 g weight, 19/22 mm ball diameters, 36-slot encoder wheels, 940 nm LEDs, 200 Hz sampling, 10 in/s tracking speed, 50/100 mA draw, Pantone 423C, named optical-retrofit product, 6-million-unit production estimate and the month... |
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| image = [[File:Apple-ADB-mouse.jpg|250px]] | | image = [[File:Apple-ADB-mouse.jpg|250px]] | ||
| caption = Apple Desktop Bus Mouse II (Model M2706) | | caption = Apple Desktop Bus Mouse II (Model M2706) | ||
| manufacturer = Apple Computer, Inc. | | manufacturer = Apple Computer, Inc. (built by Logitech and by Mitsumi) | ||
| type = Pointing device | | type = Pointing device | ||
| release date = | | release date = 1993 | ||
| discontinued = | | discontinued = 1998 | ||
| interface = [[Apple Desktop Bus]] | | interface = [[Apple Desktop Bus]] | ||
| compatible = | | compatible = ADB-equipped Macintosh computers and the Apple IIGS | ||
| predecessor = [[Apple Desktop Bus Mouse]] | | predecessor = [[Apple Desktop Bus Mouse]] | ||
| model = M2706 | |||
| model = M2706 | |||
}} | }} | ||
<templatestyles src="Template:StyledTable/styles.css" /> | |||
The '''Apple Desktop Bus Mouse II''' (model M2706) replaced the [[Apple Desktop Bus Mouse]] as the standard Macintosh mouse. Deskthority dates it to '''1993–1998''' and gives the FCC ID as '''BCGM2706'''.<ref name="dt">"Apple Desktop Bus Mouse II", [https://deskthority.net/wiki/Apple_Desktop_Bus_Mouse_II Deskthority wiki]. Part number M2706; FCC ID BCGM2706; manufacture by '''Logitech''' and by '''Mitsumi'''; one button; ambidextrous; opto-mechanical sensor; ADB interface; introduced 1993, discontinued 1998; the design inspiration from the third-generation Microsoft mouse and the resulting "tear-drop" nickname; and the two documented internal variants — Logitech with a smaller printed label, a ''single'' screw underneath, serial numbers beginning 'L' (second letter 'C' for China), embossed text in the plastic and ''two'' separate circuit boards, one for the Omron microswitch and one for the sensors and electronics; and Mitsumi with a large printed label, ''two'' small screws underneath, serial numbers beginning 'M' (second letter 'I' for Ireland, 'B' for Malaysia) and a ''single'' circuit board. Also the black version sold for the Macintosh TV and the black Macintosh Performa 5420, with both grey and black labels observed, and the photographed observation that the Mitsumi mouse has a narrower gap between the button and the top shell. '''Community wiki, cited as a secondary source''', photograph-backed.</ref> It is a one-button, ambidextrous, opto-mechanical mouse — the same formula as its predecessor in a different shell. | |||
The ''' | The shape was '''inspired by the third-generation Microsoft mouse''': rounder, with the ball forward of centre and a larger button covering the front. It is universally nicknamed the '''"tear-drop mouse"'''.<ref name="dt" /> | ||
== | == Variants == | ||
'''There are two documented internal designs, not four''', and telling them apart takes only a look at the underside. | |||
{| class="wikitable styled-table" style="width:95%;" | |||
|+'''Identifying the manufacturer'''<ref name="dt" /> | |||
! !! Logitech !! Mitsumi | |||
{| class="wikitable" style="width: | |||
|+''' | |||
! | |||
|- | |- | ||
| | | '''Label''' || Smaller printed label || Large printed label | ||
|- | |- | ||
| | | '''Screws underneath''' || '''One''' || '''Two''' small screws | ||
|- | |- | ||
| | | '''Serial number''' || Starts '''L'''; second letter indicates country — '''C''' = China || Starts '''M'''; second letter '''I''' = Ireland, '''B''' = Malaysia | ||
|- | |- | ||
| | | '''Case''' || Embossed text in the plastic || — | ||
|- | |- | ||
| | | '''Boards inside''' || '''Two''' — one for the Omron microswitch, one for the sensors and electronics || '''One''' single board | ||
|- | |- | ||
| | | '''External tell''' || Wider gap between button and top shell || '''Narrower gap''' between button and top shell | ||
|} | |} | ||
= | The board count is the practically important difference: a Logitech mouse has a separate switch board, so a failed microswitch can be dealt with without disturbing the optics, while on a Mitsumi mouse everything is on one board.<ref name="dt" /> | ||
''' | === Black version === | ||
A black M2706 was sold for the '''[[Macintosh TV]]''' and the '''black Macintosh Performa 5420''', which also got a black [[Apple Design Keyboard|AppleDesign Keyboard]]. '''Both grey and black labels have been seen on black mice''', so the label colour is not a reliable authenticity check.<ref name="dt" /> | |||
''' | '''No separate "M2707 PowerBook Gray" model is documented''' by any source consulted here, and none is claimed on this page. | ||
== How It Tracks == | |||
= | The mechanism is Apple's standard opto-mechanical arrangement, described in full in ''Guide to the Macintosh Family Hardware'':<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": Table 8-1 connector signal assignments (470 Ω pull-up, POWER.ON on pin 2); Table 8-2 transceiver electrical characteristics; Table 8-4 register 0 in the Apple Standard Mouse and its note on 100 ±10 / 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 and the $0002 → $0003 Device Handler ID change for right-hand Option and Control; Table 8-13 command byte syntax; Table 8-14 the full ADB timing specification; Table 8-15 device register 3; Table 8-16 device addresses; Table 8-17 reserved Device Handler IDs; the 500 mA total bus limit, the 5 m / 100 pF-per-metre cable limits, the 11 ms idle polling interval and the warning against unplugging a device while the computer is running. Chapter 9, "Floppy Disk Interfaces": Table 9-1 drive capacities, file systems and encoding; the IWM and SWIM interface ICs; internal 20-pin and external DB-19 pinouts; drive current requirements; and the PWM motor-speed line used only by 400K single-sided drives.</ref> a rubber-coated steel ball turns two capstans, each driving a slotted '''interrupter wheel'''; two beams of infrared light shine through the slots onto two detectors offset just enough that the two square waves they produce are '''90° out of phase''' — the ''interrupt'' signal and the ''quadrature'' signal. Which leads tells the mouse which way the wheel is turning. | ||
This is why '''a mouse with one dirty detector jitters and reverses rather than simply losing motion''': partial obstruction of one detector corrupts the phase relationship rather than reducing sensitivity. | |||
A microprocessor in the mouse counts the edges and also acts as the mouse's ADB transceiver.<ref name="gmfh" /> | |||
== | == ADB Behaviour == | ||
Apple's published figures for the Apple Standard Mouse apply:<ref name="gmfh" /> | |||
* '''Default address $03''', the address Apple reserves for relative-position devices. | |||
* '''Register 0''' is a single 16-bit quantity: bit 15 button status (0 = down), bits 14–8 '''Y''' move counts, bit 7 '''not used, always 1''', bits 6–0 '''X''' move counts. Both move fields are '''7-bit two's complement''', so the range per report is '''−64 to +63'''. | |||
* '''Resolution is 100 ±10 counts per inch at Device Handler ID $0001 and 200 ±10 at $0002'''; the mouse powers up and resets at $0001. A driver moves it to the higher mode by writing a new Handler ID to register 3. | |||
* A device must answer a Talk command within '''260 µs'''. In the idle state the transceiver repeats the last Talk command '''every 11 ms'''. | |||
The first byte carries '''Y''', not X. Bit 7 is fixed at 1 and is not a second button. | |||
'''Apple published no ball diameter, encoder slot count, sampling rate, maximum tracking speed or per-device current figure for this mouse''', and none are stated here. Figures such as "36-slot encoder wheels", "200 Hz mechanical sampling", "10 inches per second" and "50 mA typical, 100 mA maximum" could not be traced to any source and are not reproduced. What Apple does specify is a '''bus''' limit: all ADB devices combined must draw no more than '''500 mA'''.<ref name="gmfh" /> | |||
== Disassembly == | |||
= | Match the procedure to the variant:<ref name="dt" /> | ||
* '''Logitech (one screw).''' The single screw is under the label. Remove it, then release the internal clips. | |||
* '''Mitsumi (two screws).''' Both small screws are under the label. Remove them and separate the halves. | |||
In both cases the label has to be lifted or pierced. Lift it carefully from one edge with a plastic spudger if you want to keep it — the serial number on it is the only way to identify the manufacturer without opening the mouse again. | |||
== Troubleshooting == | |||
== | === Erratic or reversing cursor === | ||
By far the most common fault, and almost always dirt on the interrupter wheels or the optical pairs rather than anything electrical.<ref name="gmfh" /> | |||
# Remove the ball and inspect the wheels for dust and lint. | |||
# Clean the wheels with a cotton swab and 90%+ isopropyl alcohol; clear the slots with compressed air. | |||
# '''Clean both the emitter and the detector on each axis.''' Cleaning only one is the classic half-fix and leaves the phase relationship corrupted. | |||
# Check the capstans for a ring of compacted grime — that, not a worn ball, is what usually causes slipping. | |||
# Do not flood the optical parts with anything that leaves a film. | |||
=== | === Cursor moves on one axis only === | ||
One interrupter wheel, one emitter, or one detector. Swap your attention between the two axes and compare; the mechanism is identical on each, so a working axis is a reference. | |||
== | === Button faults === | ||
The button acts on an Omron microswitch.<ref name="dt" /> Measure across the switch terminals: effectively zero when pressed, open when released. Check for mechanical obstruction in the button lever before condemning the switch. | |||
= | On a '''Logitech''' mouse the switch is on its own board, which makes replacement considerably less risky.<ref name="dt" /> Omron D2F-series switches are the usual modern substitute. '''Apple and Omron published no rated operating life for the original''', and the "1 million clicks" figure that circulates is not reproduced here. | ||
=== | === No response at all === | ||
# Measure '''+5 V at pin 3 against pin 4''' of the ADB connector. | |||
# '''Pin 1 should idle high''', held up by the '''470 Ω''' pull-up on the computer's logic board.<ref name="gmfh" /> A pin 1 at 0 V with nothing plugged in is a fault on the computer. A bus held low for more than 3 ms is a permanent Global Reset and nothing will enumerate. | |||
# Check continuity of all four conductors end to end, flexing the cable at the strain relief — the most common failure point. | |||
# With a scope: look for the '''800 µs Attention''' pulse followed by the '''65 µs Sync''' high, and for the mouse answering within '''260 µs''' of a Talk command.<ref name="gmfh" /> | |||
=== | === Hot-plugging === | ||
Apple's warning is explicit: '''do not unplug and reattach an ADB device while the computer is running.''' The device reverts to its default address while the computer carries on trying to reach it at the address assigned at startup, so it simply stops working until the machine restarts.<ref name="gmfh" /> On many machines the ADB +5 V feed is also fused on the logic board and hot-plugging can open it; the rating varies by model, so check that machine's service documentation rather than assuming. | |||
=== | === Preventive maintenance === | ||
Clean the ball and the capstans when tracking starts to feel notchy. '''That is the only routine maintenance this mouse needs.''' Scheduled monthly, quarterly and annual strip-downs are not a manufacturer recommendation and serve mainly to wear out the case clips. | |||
== | == Modern Use == | ||
ADB-to-USB conversion keeps the mouse original. Replacement logic boards that fit the original shell and present as an ADB mouse while using a modern optical sensor have been produced by people in the retrocomputing community; these are small-batch projects that come and go, so no particular one is endorsed here. Check current sources before buying, and check that whatever you find implements the timing in [[Apple Desktop Bus]] rather than approximating it. | |||
== | == Collector Notes == | ||
* '''Manufacturer''' is read from the first letter of the serial number: L = Logitech, M = Mitsumi.<ref name="dt" /> | |||
* '''Country''' is the second letter: C = China, I = Ireland, B = Malaysia.<ref name="dt" /> | |||
* '''Label colour does not authenticate a black mouse''' — both grey and black labels occur.<ref name="dt" /> | |||
* Case yellowing is normal for ABS of this era; see [[Retrobrite]] before attempting anything. | |||
'''No production figures were ever published''' for the M2706, and the "over 6 million units, 95% platinum, under 2% black" split that circulates could not be traced to any source. It is not repeated here. | |||
== See Also == | == See Also == | ||
* [[Apple Desktop Bus]] | * [[Apple Desktop Bus]] | ||
* [[Apple Desktop Bus Mouse]] | * [[Apple Desktop Bus Mouse]] | ||
* [[Apple | * [[Apple Design Keyboard]] | ||
== References == | |||
<references /> | |||
{{Navbox-AppleVintageAccessories}} | {{Navbox-AppleVintageAccessories|state=collapsed}} | ||
[[Category:Apple Vintage Accessories]] | [[Category:Apple Vintage Accessories]] | ||
[[Category:Apple Desktop Bus]] | [[Category:Apple Desktop Bus]] | ||
Revision as of 19:11, 23 September 2026
| Apple Desktop Bus Mouse II | |
|---|---|
 |
|
| Apple Desktop Bus Mouse II (Model M2706) | |
| Manufacturer | Apple Computer, Inc. (built by Logitech and by Mitsumi) |
| Type | Pointing device |
| Discontinued | 1998 |
| Interface | Apple Desktop Bus |
| Compatible | ADB-equipped Macintosh computers and the Apple IIGS |
| Predecessor | Apple Desktop Bus Mouse |
| Model | M2706 |
The Apple Desktop Bus Mouse II (model M2706) replaced the Apple Desktop Bus Mouse as the standard Macintosh mouse. Deskthority dates it to 1993–1998 and gives the FCC ID as BCGM2706.[1] It is a one-button, ambidextrous, opto-mechanical mouse — the same formula as its predecessor in a different shell.
The shape was inspired by the third-generation Microsoft mouse: rounder, with the ball forward of centre and a larger button covering the front. It is universally nicknamed the "tear-drop mouse".[1]
Variants
There are two documented internal designs, not four, and telling them apart takes only a look at the underside.
| Logitech | Mitsumi | |
|---|---|---|
| Label | Smaller printed label | Large printed label |
| Screws underneath | One | Two small screws |
| Serial number | Starts L; second letter indicates country — C = China | Starts M; second letter I = Ireland, B = Malaysia |
| Case | Embossed text in the plastic | — |
| Boards inside | Two — one for the Omron microswitch, one for the sensors and electronics | One single board |
| External tell | Wider gap between button and top shell | Narrower gap between button and top shell |
The board count is the practically important difference: a Logitech mouse has a separate switch board, so a failed microswitch can be dealt with without disturbing the optics, while on a Mitsumi mouse everything is on one board.[1]
Black version
A black M2706 was sold for the Macintosh TV and the black Macintosh Performa 5420, which also got a black AppleDesign Keyboard. Both grey and black labels have been seen on black mice, so the label colour is not a reliable authenticity check.[1]
No separate "M2707 PowerBook Gray" model is documented by any source consulted here, and none is claimed on this page.
How It Tracks
The mechanism is Apple's standard opto-mechanical arrangement, described in full in Guide to the Macintosh Family Hardware:[2] a rubber-coated steel ball turns two capstans, each driving a slotted interrupter wheel; two beams of infrared light shine through the slots onto two detectors offset just enough that the two square waves they produce are 90° out of phase — the interrupt signal and the quadrature signal. Which leads tells the mouse which way the wheel is turning.
This is why a mouse with one dirty detector jitters and reverses rather than simply losing motion: partial obstruction of one detector corrupts the phase relationship rather than reducing sensitivity.
A microprocessor in the mouse counts the edges and also acts as the mouse's ADB transceiver.[2]
ADB Behaviour
Apple's published figures for the Apple Standard Mouse apply:[2]
- Default address $03, the address Apple reserves for relative-position devices.
- Register 0 is a single 16-bit quantity: bit 15 button status (0 = down), bits 14–8 Y move counts, bit 7 not used, always 1, bits 6–0 X move counts. Both move fields are 7-bit two's complement, so the range per report is −64 to +63.
- Resolution is 100 ±10 counts per inch at Device Handler ID $0001 and 200 ±10 at $0002; the mouse powers up and resets at $0001. A driver moves it to the higher mode by writing a new Handler ID to register 3.
- A device must answer a Talk command within 260 µs. In the idle state the transceiver repeats the last Talk command every 11 ms.
The first byte carries Y, not X. Bit 7 is fixed at 1 and is not a second button.
Apple published no ball diameter, encoder slot count, sampling rate, maximum tracking speed or per-device current figure for this mouse, and none are stated here. Figures such as "36-slot encoder wheels", "200 Hz mechanical sampling", "10 inches per second" and "50 mA typical, 100 mA maximum" could not be traced to any source and are not reproduced. What Apple does specify is a bus limit: all ADB devices combined must draw no more than 500 mA.[2]
Disassembly
Match the procedure to the variant:[1]
- Logitech (one screw). The single screw is under the label. Remove it, then release the internal clips.
- Mitsumi (two screws). Both small screws are under the label. Remove them and separate the halves.
In both cases the label has to be lifted or pierced. Lift it carefully from one edge with a plastic spudger if you want to keep it — the serial number on it is the only way to identify the manufacturer without opening the mouse again.
Troubleshooting
Erratic or reversing cursor
By far the most common fault, and almost always dirt on the interrupter wheels or the optical pairs rather than anything electrical.[2]
- Remove the ball and inspect the wheels for dust and lint.
- Clean the wheels with a cotton swab and 90%+ isopropyl alcohol; clear the slots with compressed air.
- Clean both the emitter and the detector on each axis. Cleaning only one is the classic half-fix and leaves the phase relationship corrupted.
- Check the capstans for a ring of compacted grime — that, not a worn ball, is what usually causes slipping.
- Do not flood the optical parts with anything that leaves a film.
Cursor moves on one axis only
One interrupter wheel, one emitter, or one detector. Swap your attention between the two axes and compare; the mechanism is identical on each, so a working axis is a reference.
Button faults
The button acts on an Omron microswitch.[1] Measure across the switch terminals: effectively zero when pressed, open when released. Check for mechanical obstruction in the button lever before condemning the switch.
On a Logitech mouse the switch is on its own board, which makes replacement considerably less risky.[1] Omron D2F-series switches are the usual modern substitute. Apple and Omron published no rated operating life for the original, and the "1 million clicks" figure that circulates is not reproduced here.
No response at all
- Measure +5 V at pin 3 against pin 4 of the ADB connector.
- Pin 1 should idle high, held up by the 470 Ω pull-up on the computer's logic board.[2] A pin 1 at 0 V with nothing plugged in is a fault on the computer. A bus held low for more than 3 ms is a permanent Global Reset and nothing will enumerate.
- Check continuity of all four conductors end to end, flexing the cable at the strain relief — the most common failure point.
- With a scope: look for the 800 µs Attention pulse followed by the 65 µs Sync high, and for the mouse answering within 260 µs of a Talk command.[2]
Hot-plugging
Apple's warning is explicit: do not unplug and reattach an ADB device while the computer is running. The device reverts to its default address while the computer carries on trying to reach it at the address assigned at startup, so it simply stops working until the machine restarts.[2] On many machines the ADB +5 V feed is also fused on the logic board and hot-plugging can open it; the rating varies by model, so check that machine's service documentation rather than assuming.
Preventive maintenance
Clean the ball and the capstans when tracking starts to feel notchy. That is the only routine maintenance this mouse needs. Scheduled monthly, quarterly and annual strip-downs are not a manufacturer recommendation and serve mainly to wear out the case clips.
Modern Use
ADB-to-USB conversion keeps the mouse original. Replacement logic boards that fit the original shell and present as an ADB mouse while using a modern optical sensor have been produced by people in the retrocomputing community; these are small-batch projects that come and go, so no particular one is endorsed here. Check current sources before buying, and check that whatever you find implements the timing in Apple Desktop Bus rather than approximating it.
Collector Notes
- Manufacturer is read from the first letter of the serial number: L = Logitech, M = Mitsumi.[1]
- Country is the second letter: C = China, I = Ireland, B = Malaysia.[1]
- Label colour does not authenticate a black mouse — both grey and black labels occur.[1]
- Case yellowing is normal for ABS of this era; see Retrobrite before attempting anything.
No production figures were ever published for the M2706, and the "over 6 million units, 95% platinum, under 2% black" split that circulates could not be traced to any source. It is not repeated here.
See Also
References
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 "Apple Desktop Bus Mouse II", Deskthority wiki. Part number M2706; FCC ID BCGM2706; manufacture by Logitech and by Mitsumi; one button; ambidextrous; opto-mechanical sensor; ADB interface; introduced 1993, discontinued 1998; the design inspiration from the third-generation Microsoft mouse and the resulting "tear-drop" nickname; and the two documented internal variants — Logitech with a smaller printed label, a single screw underneath, serial numbers beginning 'L' (second letter 'C' for China), embossed text in the plastic and two separate circuit boards, one for the Omron microswitch and one for the sensors and electronics; and Mitsumi with a large printed label, two small screws underneath, serial numbers beginning 'M' (second letter 'I' for Ireland, 'B' for Malaysia) and a single circuit board. Also the black version sold for the Macintosh TV and the black Macintosh Performa 5420, with both grey and black labels observed, and the photographed observation that the Mitsumi mouse has a narrower gap between the button and the top shell. Community wiki, cited as a secondary source, photograph-backed.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 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": Table 8-1 connector signal assignments (470 Ω pull-up, POWER.ON on pin 2); Table 8-2 transceiver electrical characteristics; Table 8-4 register 0 in the Apple Standard Mouse and its note on 100 ±10 / 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 and the $0002 → $0003 Device Handler ID change for right-hand Option and Control; Table 8-13 command byte syntax; Table 8-14 the full ADB timing specification; Table 8-15 device register 3; Table 8-16 device addresses; Table 8-17 reserved Device Handler IDs; the 500 mA total bus limit, the 5 m / 100 pF-per-metre cable limits, the 11 ms idle polling interval and the warning against unplugging a device while the computer is running. Chapter 9, "Floppy Disk Interfaces": Table 9-1 drive capacities, file systems and encoding; the IWM and SWIM interface ICs; internal 20-pin and external DB-19 pinouts; drive current requirements; and the PWM motor-speed line used only by 400K single-sided drives.