Macintosh: External Floppy Drive Connector Pinouts

What are the pinouts for the External Disk Drive Connector?
This article has been archived and is no longer updated by Apple.


The external floppy disk drive connector is featured on the Macintosh 128K, 512K, 512K enhanced, Plus, SE, SE/30, Classic, Classic II, IIcx, IIci, IIsi, Portable, and Performa 200.

A Macintosh 400K External Drive can be connected to the Macintosh 128K, 512K, 512K enhanced, Plus, SE, and Portable.

A Macintosh 800K External Drive or an Apple 3.5 Drive can be connected to the Macintosh 512K enhanced, Plus, SE, SE/30, Classic, Classic II, IIcx, IIci, IIsi, and Performa 200.

An Apple SuperDrive can be connected to the Macintosh SE (with SuperDrive upgrade), SE/30, Classic, Classic II, IIcx, IIci, IIsi, and Performa 200

An Apple Hard Disk 20 can be connected to a Macintosh 512K, 512K enhanced, Plus, and SE.


Connector type: DB-19.

Pin Name Description/Notes



. 1 CGND Chassis ground

. 2 CGND Chassis ground

. 3 CGND Chassis ground

. 4 CGND Chassis ground

. 5 -12V

. 6 +5V

. 7 +12V

. 8 +12V

. 9 N/C Not connected

. 10 PWM Regulates speed of the drive

. 11 PH0 Control line to send commands to drive

. 12 PH1 Control line to send commands to drive

. 13 PH2 Control line to send commands to drive

. 14 PH3 Control line to send commands to 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
Published Date: Feb 18, 2012