# Apple Macintosh XL Serial B

25 PIN D-SUB CONNECTOR

Pin | Name | Description
--- | --- | ---
1 | GND | Ground
2 | TxD- | Transmit Data line
3 | RxD- | Receive Data line
4 | n/c | Not connected
5 | n/c | Not connected
6 | HSK/DSR | TRxCB or CTSB
7 | GND | Ground
8 | n/c | Not connected
9 | n/c | Not connected
10 | n/c | Not connected
11 | n/c | Not connected
12 | n/c | Not connected
13 | n/c | Not connected
14 | n/c | Not connected
15 | n/c | Not connected
16 | n/c | Not connected
17 | n/c | Not connected
18 | n/c | Not connected
19 | RxD+ | Receive Data line
20 | TxD+/DTR | Connected to DTRB
21 | n/c | Not connected
22 | n/c | Not connected
23 | n/c | Not connected
24 | n/c | Not connected
25 | n/c | Not connected

Contributor: Joakim Ögren

Source:
Technote HW19: Pinouts at Apple Technical Notes

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May be copied and redistributed, partially or in whole, as appropriate.
Document last modified: 2000-07-09