Apple Mouse IIc
| Apple Mouse IIc | |
|---|---|
 |
|
| Apple Mouse IIc | |
| Manufacturer | Apple Computer, Inc. |
| Type | Computer mouse |
| Interface | DB-9 (the Apple IIc's shared mouse and joystick port) |
| Compatible | Apple IIc; also the Macintosh 128K to Plus, and the Apple IIe with a mouse card |
| Model | A2M4015, A2M4035 (M0100 hardware) |
The Apple Mouse IIc is the Apple Mouse (M0100) sold for the Apple IIc. Deskthority lists the M0100, A2M4015, A2M4035 and A2M2050 as the same mouse under different part numbers.[1] The mechanism, connector pinout and signals are on the Apple Mouse page. What is particular to the IIc is that some M0100 mice do not work on it.
The compatibility problem
[edit | edit source]The first Macintosh computers had a DB-9 connector for the mouse. The Apple IIc, released a few months later, used the same port for its optional mouse, but the port also had to support joysticks, and the changes made for the joystick stop some M0100 mice working. The symptoms are "buttons working, but movement in some directions not possible and/or jerky".[2] A mouse that clicks but will not move in some directions on a IIc, while working on a Macintosh Plus, has this problem; a mouse that does nothing at all has a different fault.
The cause is drive strength. The IIc's mouse inputs are shared with an NE556 timer. The Mitsumi-built M0100 board uses a µPC339 quad comparator (an LM339) with open-collector outputs pulled up through 3.3 kΩ resistors, which cannot move those inputs far enough. The Alps-built board uses a 74LS14 hex Schmitt-trigger inverter with push-pull outputs and works. Replacing the 3.3 kΩ pull-ups with 1 kΩ does not fix it: on an oscilloscope the inputs still barely moved.[3]
The IIc does not identify a mouse by resistance: the resistors on the Mitsumi board are the 3.3 kΩ pull-ups of its open-collector outputs.[3]
Identifying the variant
[edit | edit source]| Board | Screws on the underside | Output stage | Works on a IIc |
|---|---|---|---|
| Alps | 1 | 74LS14, push-pull | Yes |
| Alps circuitry, Apple-silkscreened board | 1 | 74LS14, push-pull | Yes, confirmed on an early A2S4000 IIc |
| Older "Made in U.S.A.", Apple-marked board, older-style plug | 2 | No buffer IC: 3-pin optical sensors with push-pull outputs, no pull-ups | Yes |
| Mitsumi | 2 | µPC339 open collector with 3.3 kΩ pull-ups | No |
Two screws alone do not identify a Mitsumi mouse, because the older US-built board also has two; the label settles it. Apple's archived note "Mouse Compatibility: Macintosh Plus and Apple II Computers" distinguishes a mouse "Made in the US" that works on both machines from one "Made in Japan", which matches the Alps and Mitsumi labels. Cord part numbers and board connectors also differ between variants, so cables are not interchangeable.[3]
Fixes
[edit | edit source]External adapter
[edit | edit source]An adapter between the mouse and the IIc buffers the four movement signals (direction X/Y and step X/Y) into push-pull outputs, leaving the mouse unmodified. The approach first published on vcfed.org used the four AND gates of a 74LS08; raphnet's adapter uses a 74LS125 buffer and needed no pull-up or pull-down resistors. Raphnet has also sold assembled adapters.[2]
Chip swap
[edit | edit source]On a Mitsumi board:[3]
- Replace the µPC339 with a TLC3704IN, a pin-compatible quad comparator in the same 14-pin DIP package with push-pull outputs that can source or sink 20 mA.
- Remove the 3.3 kΩ pull-up resistors, which are redundant with the new part.
Anderson made this change on three Mitsumi mice and tested them on an Apple IIc, an Apple IIe with a mouse card and a Macintosh Plus.[3]
Other faults
[edit | edit source]Cleaning, the direction-decoding table and the connector pinout are on Apple Mouse.
See also
[edit | edit source]References
[edit | edit source]- ↑ "Apple Mouse", Deskthority wiki. Lists Apple M0100, A2M4015, A2M4035 and A2M2050 as bus mice for the Apple IIc, Apple III and early Macintosh, "same as the 'Macintosh Mouse', only renamed". Community wiki, cited as a secondary source.
- ↑ 2.0 2.1 Raphael Assenat, "M0100 Mouse adapter for Apple IIc", raphnet.net. Symptom description; the 74LS08 buffer approach credited to a vcfed.org post by jmetal88; the author's 74LS125 adapter, which needed no pull-up or pull-down resistors.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Glenn Anderson, "Apple IIc mouse compatibility: some details, schematics, and a chip swap to fix compatibility", TinkerDifferent, from 15 September 2024. Four M0100 mice opened, drawn as KiCad schematics and tested; the 1 kΩ pull-up test; the TLC3704IN swap tested on three Mitsumi mice with an Apple IIc, an Apple IIe with mouse card and a Macintosh Plus; Apple's archived note "Mouse Compatibility: Macintosh Plus and Apple II Computers". Community research, cited as a secondary source.