Apple Macintosh and Newton serial connection

 8  7  6
 °  °  °
5    4  3
°    °  °
  2   1
  °   °
Miniature DIN-8 jack
(female without pins)
Viewed from outside of computer
Macs and Newtons always have a female jack on the computer
PinRS-422 signal nameDirectionRemarks
1Handshake output DTRHSKoVoltage from Mac
2Handshake input CTSHSKiInput to Mac
3Transmit data -TxD-Voltage from Mac(use this pin when connecting to RS-232)
4Frame groundGND
5Receive data -RxD-Input to Mac(use this pin when connecting to RS-232)
6Transmit data +TxD+Voltage from Mac(leave open for RS-232)
7Gen. Purpose Input or no connectionGPiInput to Mac(Sometimes connected to DCD on modem)
8Receive data +RxD+Input to Mac(connect to ground for RS-232)

The mating DIN-8 plug is listed in the Mouser Electronics (800-346-6873) catalog as stock number 171-2508 ($1.52). It's also available from Digi-Key (800-344-4539) as part no. CP-2080-ND ($1.22). (Both these vendors charge a $5.00 fee for orders less than $20 or $25.) However, the DIN-8 plugs are small and hard to solder. Instead, buy a long Mac printer cable and cut it in half to get two cables pre-assembled to DIN-8 plugs.

To connect two Macs to each other or to connect a Mac to a Newton, use a Mac printer cable. When Macs are connected to each other using a printer cable, you need to use a communications program to send files between the computers. A more elegant solution is to use AppleTalk networking (which is built-in on Macs) on LocalTalk or PhoneNet connectors. This lets you share printers and the drive in one computer can appear on the desktop of the other. AppleTalk connections can also be used to connect a Newton to a Mac.

The modem port (also called the "GeoPort") on the Quadra 840AV and Quadra/Centris 660AV has an additional pin. However, the 8-pin DIN plug mates with that 9-pin jack. The GeoPort is also on the Power Macintosh 6100 series, 7100 series, 7200 series, 7500/100, 8100 series, 8500/120, and 9500 series.

The new iMac does not have a serial connection but can be used with an external USB-to-serial adapter, available from third parties. It does not have a port for LocalTalk or PhoneNet but does support AppleTalk on Ethernet.

[Pin-out for old Mac 128/512K with DB-9 jacks for modem and printer ports.]

Mac or Newton to IBM PC (9-pin) cable

I bought the DIN-8 male to DB-9 female cable from MacMall. However, Bill Indest,, wrote that they don't carry it anymore.

Max Glaskin,, wrote:

Xemplar sells the PC to eMate cable for £9.00 (about US$14.50) and adds another £1.00 (US$1.60) for postage and packing. On top of this, customers within European Union countries have to pay Value Added Tax of 17.5%.

Xemplar only sells to educational establishments such as schools and colleges. I told them I had children at school and the cable was necessary to help them complete their studies, which is true.

Xemplar Education Ltd, The Quorum, Barnwell Road, Cambridge CB5 8RE, UK. Tel +44 (0)1223 724724. Fax +44 (0)1223 724324.

Lindy ( ... has one cable in its catalogue, part no. 30 249, which is an 8 pin Mini DIN male to 9 way D female, with a price of £4.75 plus tax of 17.5%, which totals about US$9. Lindy will only handle orders with a minimum value of £30 (US$48) but they have lots of other useful accessories in their catalogue so reaching that total shouldn't be onerous.

... Lindy's say their cable is identical [to what is shown below] except for one thing - pin 2 of the DIN-8 Male is connected to pin 7, ... not pin 4, ... of the DB-9 Female.

I ran NEWTINST.EXE (see below) on a PC with Windows 3.1 and observed the handshake lines on the com port. Both RTS (pin 7) and DTR (pin 4) were asserted so the Lindy cable should work.

The catalog for MCM Electronics lists an "Apple Mac to Serial Adapter Cable" (order # 83-2330) described as "mini DIN 8 pin male to DB-9 female." I haven't tried it but it may work. MCM's phone number is 800-543-4330. The price in the catalog is $6.19 plus shipping. Orders under $20 are charged a $5 service fee.

If you want to build the cable, here is the pin-out:

DIN-8 Male PinDB-9 Female PinPC Signal NameRemarks
16DSRHandshake from Mac to PC
2 (or 2 and 7)4DTRHandshake from PC to Mac
32Receive dataData from Mac to PC
4 (or 4 and 8)5Ground
53Transmit dataData from PC to Mac
Data from my measurement of cable purchased from MacMall. The PC usually has a male DB-9 plug so this cable should have a female jack.

Mac or Newton to IBM PC (25-pin) cable

DIN-8 Male PinDB-25 Female PinPC Signal NameRemarks
16DSRHandshake from Mac to PC
2 and 720DTRHandshake from PC to Mac
33Receive dataData from Mac to PC
4 and 87Signal ground
52Transmit dataData from PC to Mac
No connection4, 5RTS, CTSJumper in connector on PC end

DIN-8 to DB-25 data from ohmeter measurement by Brian Wood,, of cable furnished in Newton Connection Kit.

New - October 1, 2003 - MCM Electronics offers a Macintosh Printer Cable, DB-25 male to 8-pin male. I haven't tried it but it's only $0.49.

Package Installers

Newton OS 1.x

Get the Windows Package Installer (NEWTINST.EXE) at

NEWTINST.EXE works under Windows 3.1. However, I do not know of anyone who has used it successfully under Windows 95. If you get it to work under Win95, please send a message to me.

Apple's Newton Connection Kit for Windows works under Win95. It comes with a cable so you probably would not be reading this if you had it.

Mac users can install packages with PDA Package Downloader or Apple's Newton Connection Kit for Macintosh.

Newton OS 2.x

The Newton Backup Utility will install packages and backup the Newton.

For other useful PC utilities, see Clay Irving's PC Utilities for the Newton

Morgan Nichol made an adapter to connect his Message Pad to his PC. His adapter has a female DIN-8, so the male DIN-8 to male DIN-8 cable that came with the Message Pad plugs into his adaptor. He posted a page showing the pin-out he used and photos of his adapter at

Please send your comments and suggestions.
John Neuhaus, WA2JXE

Last revised: Wed, Oct 1, 2003