I recently got a Apple Power Macintosh 6100 for free. It powers up and seems to work, so I want to try it out and see what it's like. Unfortunately, the important ports and connectors are "non-standard", which means I can't directly hook up the things I have:

Rear of PowerMac

I'd like to connect a standard monitor (With VGA, S-Video, or something else which have), as well as a keyboard and mouse (I have some PS/2 keyboards an mice lying around). There seem to be adapters for HDI-45 to VGA, but I want to do this without buying any additional parts (i.e. free). I'm comfortable with soldering and making things, as well as electronics in general.

Is there a way to connect a more "Standard" display, keyboard, and mouse to this computer? and, if so, how do I do this?

Is there anything else I should be aware of?

  • 1
    Once you get past video and keyboard access, the network interface <---> connector is called AAUI wiki-link and is 10Mbit if I remember correctly. You may find it easier to find a NuBus card with 10bT twisted pair connections, however you may need to put a 10/100 switch inline to get the thing onto a gig switch. Commented Dec 10, 2016 at 22:25
  • A Mac this old probably needs it clock battery replaced too, if its bad it will not boot and you will get the sad chime. Its known as a "half-double A" battery but I don't know the official designation.
    – PhasedOut
    Commented May 26, 2017 at 21:30
  • 1
    @PhasedOut Single A battery? :-p More seriously, the 3.6V half-AA name seems to be standard.
    – wizzwizz4
    Commented Jul 15, 2017 at 11:13
  • @wizzwizz4 Just don't get it confused with the very similar sized (~1mm shorter) 4SR44 used for film cameras because that one is 6V (stack of four SR44 button cells in one outer wrapping).
    – mnem
    Commented Dec 15, 2017 at 12:41

3 Answers 3


Maybe the most difficult task is to find a plug for the Apple AudioVision connector. Here is its pinout, taken from http://pinouts.ru/Video/audiovision_pinout.shtml , in case you find a suitable connector and want to do the wiring by yourself.

Pinout diagram

1   Analog audio ground
2   Audio input shield
3   Left channel audio input
4   Right channel audio input
5   Left channel audio output
6   Right channel audio output
7   Reserved
8   Monitor ID sense line 1
9   Monitor ID sense line 2
10  Green ground (shield)
11  Green video output (75 )
12  Video input power ground
13  Power for camera +5 V
14  Reserved
15  Reserved
16  Reserved
17  Reserved
18  Monitor ID sense line 3
19  S-video input shield
20  S-video input luminance (Y)
21  S-video input chroma (C)
22  Reserved
24  Reserved
25  Reserved
26  Red ground (shield)
27  Red video output (75 )
28  I2C data signal
29  I2C clock signal
30  Reserved
31  Monitor ID
32  Monitor ID
33  Vertical sync signal
34  Composite sync signal
35  ADB power +5 V
36  ADB ground
37  ADB data
38  Keyboard switch
39  Reserved
40  Reserved
41  Monitor ID
42  Horizontal sync signal
43  Video sync ground
44  Blue ground (shield)
45  Blue video output (75 )

There seems to be some adapters that can adapt the Audiovision connector (aka HDI45) to DB15 standard Apple VGA connector, like this (taken from an eBay auction):

HDI45 to DB15 adaptor

HDI45 Plug

DB15 Socket

If you want to do it yourself, just take signals from pins 27,26 (red output and red grund), 11,10 (green output and ground), 45,44 (blue output and ground), 42 (HSYNC), 33 (VSYNC), and 43 (SYNC ground) and wire them accordingly to a VGA DE-D15 connector.

For keyboard and mouse support, you will need some sort of adapter, as the connectors, protocols and signal levels are not the same.

You may want to visit kdblabel ( www.kdblabel.org ) as they have tons of info about different protocol and signalling conventions. Hopefully, ADB is among them and you will be able to use a PIC or something similar to perform the conversion.

For mouse support, the people at GeeThree ( http://www.geethree.com/adb/index.html ) have a PS/2 to ADB mouse adapter

PS/2 to ADB adaptor

  • 1
    note that Apple "VGA" as pictured above is very different from PC VGA, which is also 15 pins but in 3 rows of 5 pins each, rather than a row of 7 and a row of 8. but there are also adapters to go from Apple 15-pin to PC 15-pin, which will allow you to use readily-available PC monitors with your Mac.
    – Ken Gober
    Commented Sep 12, 2016 at 20:38
  • Once you have the ADC to apple adapter, this additional adapter will convert the signal to VGA. retrocomputing.stackexchange.com/questions/929/… Commented Dec 10, 2016 at 21:11
  • 1
    As I mentioned in the above adapter link, Other companies than apple made adapters that have slightly different switch conventions. I have one from a monitor manufacturer(innovision) that nicely lists the switch purposes on the back of the case since macintosh monitors were almost always fixed resolution at a fixed frequency. Commented Dec 10, 2016 at 21:26
  • The 'monitor ID' pins' connections are VERY IMPORTANT because without them, the 6100 will not send any video data out (why bother: there's no monitor connected). An original adapter from HDI45 to DA-15 (two-row Apple video) doesn't suffice, your DA-15 to HD-15 (VGA video) adapter is where those ID signals are programmed (hardwire or switched).
    – Whit3rd
    Commented Dec 14, 2017 at 23:03
  • This likely isn't a "why bother" issue, it is a "some monitors back then could be permanently damaged if you fed them the wrong kind of video timing" issue - and leaving that to user technical expertise doesn't seem very Apple. Commented Jan 28, 2020 at 19:57

ADB keyboards and mice are readily available on eBay for as little as $10. Apple used ADB from 1987-1999 for Macs and the Apple IIgs so there are a lot of devices around. The monitor adapter from Apple AudioVision to VGA is harder to get and I defer to @mcleod_ideafix.

  • 2
    Some older KVM vendors had ADB converters to PS2 at the time. There is a small asic chip involved in the conversion because Apple Desktop Bus devices were active and could be daisy-chained up to 4 units. It was powered by the 5v bus. I don't believe they were serially connected like USB though and you could not add devices while the system was on without causing yourself some problems. You could remove an end device, however you could not add it back. Commented Dec 10, 2016 at 21:16

The HDI45 connector for video is essential (it is nearly impossible to tack-wire to the main circuit board). Buy a video connector adapter. They're still for sale Pi mfg. for example and probably there's a surplus supplier that can get you used ones. An important part of those adapters is the mode switch(es): you have to experiment to find a monitor mode that your Macintosh boot code recognizes and drives, which is accepted by the modern screen.

A used ADB mouse is easier to find than any adapters (to other, equally obsolete mice and keyboards). Some efforts are underway to serve USB items to ADB ports coming Real Soon Now. Finding an old keyboard/mouse in a friend's closet is your best prospect. My closets are well-stocked in that regard.

Mac OS 7.5.3 is suitable for this model; 8.1 is better, 8.6 is possible. It can boot from internal (or external) SCSI disks, including CDROM. It may be important to learn SCSI address and termination rules... the main logic board is SCSI ID=7, usually internal HD is ID=0.

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