Classic Macintosh pinouts


Normad Vaporware Inc, August 24, 1992.
Guide to Pin-out connectors to the Apple Macintosh
By Norman G. King

Hey, want to hack up cables to work with the Macintosh, but you
don’t know the pin-outs? Maybe you can get that IBM, or IEEE device to
work if only you knew the pin-outs of the Macintosh serial port?

These Pin-outs cover the original Macintosh line, the newer
Macintosh series uses different ports, so you may need an adapter in some
cases from Apple or an Apple dealer. My information only
deals with the original Macintosh ports.
The Internal drive connector has 20 pins and looks a lot like the IBM 3.5
inch drive connector. In fact, it is simular! Just that the Macintosh uses
modified drive to electronically eject the disk and the IBM doesn’t. The
top has a grove or plastic knob on it and pin 1 has a red or blue wire on
the cable so you will know were to connect it to.
Top
———__———-
Pin19|. . . . . . . . . .|Pin1
Pin20|. . . . . . . . . .|Pin2
|___________________|
1. Ground 7. Ground 13. +12 V DC 19. +12 V DC
2. Phase 0 8. Phase 3 14. Enable 20. PWM (Motor)
3. Ground 9. -12 V DC 15. +12 V DC
4. Phase 1 10. Write Request 16. Read
5. Ground 11. +5 V DC 17. +12 V DC
6. Phase 2 12. Head Select 18. Write

Keyboard connector, on early Macs it was a simple Telephone Handset
connector. You can find a replacement at any electronic shop or
Radio Shack.
_____ 1. Ground (Black Wire)
__| |__ 2. Keyboard Clock (Red Wire)
__| |__ 3. Keyboard Data (Green Wire)
| | 4. +5 V DC (Yellow Wire)
| 4 3 2 1 |
| | | | | |
|______________|

Mouse Connector, just a 9 pin serial port. Nothing special.
___________
5 \. . . . ./ 1 1. Ground 5. X1 Pulses
9 \. . . ./ 6 2. +5 V DC 6. Not Connected
——- 3. Ground 7. Switch
4. X2 Pulses 8. Y2 Pulses
9. Y1 Pulses

Power supply output pin allocations. A 11 pin connector toward the
front of the power supply and under the CRT. In the second pin
area, there is no pin in it. You can use that as a guide.

1. Composite Video 5. Vertical Synch 9. Ground
2. — No Pin — 6. +5 V DC 10. +12 V DC
3. Horizontal Synch 7. Ground 11. Battery
4. Speaker 8. -12 V DC

External Drive connector. 19 Pin connector, similar to some IBM
type external connectors on clone systems, but not quite the same
amount of pins.
______________________
Pin10\ . . . . . . . . . ./ Pin1
Pin19 \ . . . . . . . . ./ Pin11
——————
1. Ground 6. +5 V DC 11. Phase 0 16. Head Select
2. Ground 7. +12 V DC 12. Phase 1 17. Enable
3. Ground 8. +12 V DC 13. Phase 2 18. Read
4. Ground 9. Not Connected 14. Phase 3 19. Write
5. -12 V DC 10. PWM (Motor) 15. Write Request

Macintosh DB-9 RS-422 serial connector, 9 pin connector, similar to
Mouse connector. See mouse connector for picture.
1. Ground 4. Transmit Data + 7. CTS/ External Clock
2. +5 V DC 5. Transmit Data – 8. Receive Data +
3. Ground 6. +12 V DC 9. Receive Data –

DB-25 type RS-232C serial connector. Like the type the IBM series
uses, use this to connect IBM serial devices to Mac serial ports or
Mac serial devices to IBM serial ports. Works for Imagewriters
Here is the hookup:

Mac DB-9 IBM DB-25 Connect these pins!
Pin To Pin
—————————–
3 7
5 3
7 20
8 7
9 2

The IEEE-488 connector is a parallel type connector that is similar
to SCSI in some features. The HP-150 series uses a HP-IB interface
that is nothing but a 1980 version of IEEE-488, and should work.
Here is the pinout of the 24 pin IEEE-488 port:

1. Data Bit 1 7. Not Ready 13. Data Pin 5
2. Data Bit 2 8. Data Not Accepted 14. Data Pin 6
3. Data Bit 3 9. Interface Clear 15. Data Pin 7
4. Data Bit 4 10. Service Request 16. Data Pin 8
5. End or Identify 11. Attention 17. Remote Enable
6. Data Available 12. Shield 18-24. All Grounds



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