Newton Serial Adapter – DIN8 to DB9

DIN8 to DB9 Serial Cable Adapter for Newton MessagePadSo, you’ve got a Newton MessagePad, but you use a PC, and have no way to connect it up to install software & sync with other applications, install drivers, etc. The solution is a DIN8 (on the Newton end) to DB9 (on the PC end) adapter, go buy one.

Oh, not so easy is it?..

You found one but it was for a modem, and wouldn’t have worked, and the Newton was discontinued by Apple in the late nineties, so they really don’t have much to help you… Well you’re stuffed, aren’t you?

No, you’re not – make one, I did, and my soldering skills are some of the most apalling in the world.

You’ve got two choices:

  1. Make a full length cable to go from the dongle (that little black plug that sticks into the side of the Newton) to your PC.
  2. Make a little adapter, so the cable that came with your Newton with a round plug on both ends can plug into the dongle, then into your adapter, which plugs into your PC.

I went with the latter option, what you do is your choice, this page details how I did it, but I’m sure you can work out any changes you’d need to make.


  • Female DB9 socket – make sure you get a shroud as well.
  • Female DIN8 socket.
  • 6 core computer cable, more cores is fine, but you’re only going to use 5 of them anyway. You’ll probably have to buy it by the meter, but you really don’t need that much, make your one any length, 30cm is more than enough, mine is 60cm.


  • Soldering iron & solder.
  • Wire stripper.
  • Philips screw driver.
  • Something to hold parts as your work on them, I built a dodgey little vice out of my SwissTool and a hair tie that worked extremely well.
  • Pen & paper. Or notepad on your PC. Or a Newton.

About the pen & paper, you should be writing things down as you go or everything might just go to custard, this is no problem, you can easily desolder what you’ve done and build it again, but speaking from experience this is frustrating.

Step 1.

Clear your workspace.

Step 2.

Become at one with your sockets.

If you haven’t ever worked with a DIN8 or DB9 socket, have a good look at them, look at the pins on the back, make sure you know which way is up on each, work out the pin numbering – this is extremely important, every pin does a particular job, you need to connect the right pins up, and if you don’t know which is which, you won’t manage it.

To help you, here is a brief run down of each socket, and the job each pin does:

DIN8 – RS422 DB9 – RS232

  1. DTR
  2. CTS
  3. TxD
  4. GND
  5. RxD
  6. TxD+
  7. GPi
  8. Rxd+
  1. CD
  2. RxD
  3. TxD
  4. DTR
  5. GND
  6. DSR
  7. RTS
  8. CTS
  9. RI

The pins that we’ll be connecting are:

DB9 – RS232 DIN8 – RS422

2. RxD
3. TxD
4. DTR
5. GND
6. DSR

5. RxD
3. TxD
2. CTS
4. GND
1 . DTR

Those acronyms don’t really need to mean anything to you for this to work.

If you were to make a cable that plugged directly into the dongle (eg. using a male DIN8 plug) you’d need to swap pins 2 & 3 on the DB9 end.

Step 3.

Strip your wires.

There will be a tough (probably gray) outer sheath, be very careful removing this, you don’t want to damage the individual cores in the middle, only take off a couple of centimetres – this might not seem like enough, but it should do the trick, and will hopefully lead to a tidier end result.

Once you’ve done that you need to strip the coloured sheath off each of the individual strands in the middle, pick 5 strands, only strip off a couple of milimetres from the end of each, make sure you don’t snap or pull out any of the strands.

Each strand should have a particular colour, be sure you can readily distinguish between them. It doesn’t matter which colour you use, if you like orange, keep orange, if you like green keep green.

Make sure any shrouds that are going to lock over the sockets are on the cable, they should be able to just slide on, be sure they’re facing the correct direction, you won’t be able to put them on after you’ve soldered your pins. This would make you sad.

Step 4.

Lock the DB9 socket, pins upwards, in place. It doesn’t matter how you do this, but the thing might get warm – especially if you’re not very good at soldering – so you can’t really just hold it. If you have a small vice, use that. Use anything. It doesn’t matter. As long as its not flammable.

Step 5.

Start up your soldering iron.

Step 6.

Solder your wires, in any order, to these pins on the DB9 socket: 2, 3, 4, 5, 6.

I find the easiest way to do this is to melt some solder, and gently rub the wire in the solder until the end has some (but not a lot) of solder on it. Then hold the wire against the pin and momentarily touch it with the soldering iron. It’s the fastest and easiest way I’ve found to do it, and helps avoid big blobs of solder shorting out the points.

Remember, the diagram of the pin numbers above was from the front of the socket, you’re now looking at the back, so the pin numbers are reversed, assuming you have the wider side away from you, the first pin is at the far left, nothing goes on that pin, connect to every other pin on that row, and only the first (left most) pin on the next row down.

Step 7.

Write down a list of pin numbers, from 2 – 6, beside each number write the colour of the wire strand which you connected to it.

Step 8.

Work out the pin to colour map. This is very easy, but double-check yourself to make sure you’ve put the numbers in the right place. In the list you made in step 7 you’ve currently got 2 columns, add a third column, this is for which pin you’re connecting each wire to on the DIN8 end. For example, next to the colour you connected to pin 2 on the DB9 end put the number 3.

You’ll end up with something like this:

DB9 Colour DIN8



The numbers will be the same, the colours depend on you and your cable…

Step 9.

Now simply follow the colour chart you made and solder your wires to the various correct pins. The soldering on this end is somewhat trickier than the other, don’t be discouraged, you’ll manage it, even if you have to remove everything and start again.

Less solder is better than more solder, I can’t emphasise this enough, and if you use too much solder there’s a really good chance you’ll short two or more of the pins together..

Step 10.

If you have a multimeter, you should now check that all your pins go to the correct place on each end. Once you confirm that, go ahead and push or screw the shrouds into place over the plugs, take care not to tug on any of your solder connections.

Mine looks like this.

Once you’re done, plug it into your PCs serial port, then plug the apple cable into your adapter, then plug the other end of that cable into the dongle, then plug the dongle into the Newon. Sounds silly when I put it like that.

Tell you what, the first time my connection came up – it was a moment of joy.

Speaking of your connection, you’ll need some software on your computer to handle the communication, I suggest Newton Connection Utilities, they do the trick nicely (if your MessagePad is pre MP2k, you need Newton Connection Kit instead).

If you’ve got a fast PC you’ll probably also want to get a copy of Slowdown, with large file transfers your connection might time out, running Slowdown prevents this, but do remember to turn it back off when you’re done. I set it to maximum slowness, and about 25% reaction.

If you’re running linux, I’m sure you can find your own connection software and sort out any problems you run into. But you’re used to being on your own and in the dark, I’m sure.

In Newton Connection Utilities, you’ll need to make sure you select the correct port, this will probably be either ‘Com 1’ or ‘Com 2’, which it turns out to be depends on which port you plugged your adapter into.

If you build this cable, please drop me a line and let me know how you went.

The success of my cable is almost entirely thanks to John Neuhaus, his Apple serial page has great information, without his help I suspect that I never would have made it work.