Apple Data Modem 2400 (1989)
Apple introduced the Data Modem 2400 on June 12, 1989, according to its technical note TIL 4305. It is an external data modem for the Apple II and Macintosh families, not the Macintosh Portable's internal modem or the Apple Personal Modem. The note describes sales through authorised Apple Desktop Communications dealers; introduction is not treated as proof of a first shipment.

Resized, no crop or retouching.
Own functional diagram, not a photograph or enclosure drawing.
Specs
| Key feature | Data Modem 2400 |
| Introduction | June 12, 1989 (TIL 4305) |
| Rates | 300 / 1200 / 2400 bit/s |
| Standards | Bell 103 · Bell 212A · V.22A/B · V.22bis |
| Error correction | MNP classes 1–4 |
| Interface | RS-422-A · 8-pin mini-DIN |
| Serial ports | 2 ports; pass-through rated up to 56.7 kbit/s |
| Telephone connections | 2 RJ-11: line and telephone, not interchangeable |
| Settings | Nonvolatile RAM |
| Power draw | 7 W maximum (US/Canada) |
| Dimensions | 200 × 120 × 45 mm |
| Weight | 500 g without adapter |
| Receiver: sources | −10 to −45 dBm (TIL); −10 to −43 dBm (manual) |
Model and documentation
Apple introduced the Data Modem 2400 on June 12, 1989, according to its technical note TIL 4305. It is an external data modem for the Apple II and Macintosh families, not the Macintosh Portable's internal modem or the Apple Personal Modem. The note describes sales through authorised Apple Desktop Communications dealers; introduction is not treated as proof of a first shipment.
Rates and protocols
The modem supports 300 bit/s with Bell 103, 1200 bit/s with Bell 212A and V.22A/B, and 2400 bit/s with V.22bis. It implements MNP classes 1 to 4 for error correction and accepts Hayes instructions. Apple describes asynchronous, full-duplex transmission. The 2400 bit/s rate is separate from the pass-through port's 56.7 kbit/s rating in the note.
Connections and use
Two serial connectors link the computer and another device. A selector switches between active modem operation and passing the computer through to the connected device; these are not two simultaneous telephone connections. Two RJ-11 jacks serve the line and telephone. Apple warns not to interchange them: the telephone is disconnected while the modem is in use. The daisy-chain connection does not support AppleTalk devices.
Settings and sources
Settings are retained in nonvolatile RAM. The speaker has adjustable volume and the modem uses an external adapter. TIL 4306 specifies a 7 W maximum, 500 g without the adapter and 200 × 120 × 45 mm for the US and Canadian versions. Receiver range differs between originals: −10 to −45 dBm in TIL 4306, versus −10 to −43 dBm in Technical Procedures. These limits are not mixed, nor is an Apple IIc or AppleFax adapter promised to work merely because its connector fits. The image is an original functional diagram, not a photograph or enclosure drawing.
Sources
- Apple · TIL 4305 · Data Modem 2400 overview · 1989
- Apple · TIL 4306 · Data Modem 2400 specifications · 1989
- Apple · Technical Procedures · Modems · 1991 compilation, sections 2–3
- dimensionapple.com · Original schematic illustration