# Macintosh External Drive

(At the Computer)
(At the Diskdrive)

19 PIN D-SUB FEMALE at the Computer.
19 PIN D-SUB MALE at the Diskdrive.

Pin | Name | Dir | Description
--- | --- | --- | ---
1 | CGND |  | Chassis ground
2 | CGND |  | Chassis ground
3 | CGND |  | Chassis ground
4 | CGND |  | Chassis ground
5 | -12V |  | -12 VDC
6 | +5V |  | +5 VDC
7 | +12V |  | +12 VDC
8 | +12V |  | +12 VDC
9 | n/c | - | Not connected
10 | PWM | ? | Regulates speed of the drive
11 | CA0 | ? | Control line to send commands to the drive
12 | CA1 | ? | Control line to send commands to the drive
13 | CA2 | ? | Control line to send commands to the drive
14 | LSTRB | ? | Control line to send commands to the drive
15 | WrReq- | ? | Turns on the ability to write data to the drive
16 | HdSel | ? | Control line to send commands to the drive
17 | Enbl2- | ? | Enables the Rd line (else Rd is tristated)
18 | Rd |  | Data actually read from the drive
19 | Wr |  | Data actually written to the drive