Mac DIN-8 to DB-25 connector
You need a null-modem adapter. They sell them at Radio Shack. Just pick up a Mac DIN-8 to DB-25 (male) "hardware handshake" modem cable, and a DB-25 (female) to DB-25 (male)** null-modem adapter.
One SE user emailed to say that the following setup worked for him: "A Mac modem cable (Belkin #F2V088-06) connected to a null modem (Belkin #F3D153-10). The PC uses a standard modem cable. The best speed transfer is around 28.8k. Using the same setup on a Mac IIcx I get around 55.4k".
Different null modems can be wired up in different ways, so it may or may not work. Go ahead and try it....
Making your own 'hardware handshake' serial cable
Here's an account of how to make your own Mac-PC cable, again mostly clipped from Usenet (where would we be without it?).
Parts
- Macintosh serial cable (printer cable or modem cable)
- Length of 5-wire cable (as long as you need)
- DB-9 or DB-25 connector, depending on what you need to plug in your PC's serial port
- Flashlight bulb, battery and wire
Assembly
- Cut one connector off the Mac serial cable to leave a Mini DIN-8 still attached, and strip the ends of the wires.
- Use the flashlight bulb and battery to figure out which wire goes to which pin on the connector (hey, it works!). Remember which color goes to which pin. Better still, write it down.
- Solder the wires in the 5-wire cable to the PC connector. For a DB-9 connector it's one wire to the #2 pin, one to the #3 pin, one to the #5 pin, one to the #7 pin and one to the #8 pin. For a DB-25 connector it's one wire to the #2 pin, one to the #3 pin, one to the #4 pin, one to the #5 pin and one to the #7 pin. Make a note of which color goes to which pin (pins are labeled on connector).
- Assemble the casing around the PC connector.
- Attach the five wires to the respective Mac serial wires. They need to be hooked together as in the table below. (Note: Pins 4 and 8 from the Mac are both connected to the PC 'SGND' pin, that's #5 for a DB-9, #7 for a DB-25).
Mac name RS-232 name Mac DIN-8 Pin# PC DB-9 Pin# PC DB-25 Pin# -------- ----------- -------------- ------------ ------------- RxD- RD 5 ------------------------- 3 2 TD TxD- TD 3 ------------------------- 2 3 RD Ground SGND 4 ------------------------- 5 7 SGND | RxD+ DCD 8 ---------------------- HSKi CTS 2 ------------------------- 7 4 RTS HSKo RTS 1 ------------------------- 8 5 CTS - Cut back the unused Mac wires from pins #6 and #7. Insulate all bare ends and connections, attach the cable between the two computers, and you're ready to go.
You'll now need standard comms programs running on both machines to actually transfer files. Choose software that offers the Zmodem protocol (like the shareware ZTerm for the Mac). I'm told ProComm is good on the PC.
Mini DIN-8 Macintosh Serial Port Pinout
(looking at the back of the Macintosh)
/------###------\ 1 HSKo Output Handshake
/ ### \ (Zilog 8530 DTR pin)
/ \ 2 HSKi/CLK Input Handshake *OR*
/ [|] [|] [|] \ External Clock
/ 8 7 6 \ 3 TxD- Transmit data (-)
| |
| | 4 Ground Signal ground
| === === === |
| 5 4 3 | 5 RxD- Receive data (-)
| |
| | 6 TxD+ Transmit data (+)
\----+ === === +----/
\###| 2 1 |###/ 7 N/C (no connection)
\##| |##/
\| |/ 8 RxD+ Receive data (+)
\------###------/
###
Serial pinouts of various common connectors
Function Pin connections
-------- ---------------
Mac name RS-232 name Mac DB-25 DB-9 RJ-45
-------- ----------- --- ----- ---- -----
RxD- RD 5 3 2 5
TxD- TD 3 2 3 6
Ground SGND 4+8 7 5 4
HSKi CTS 2 5 8 7
HSKo RTS 1 4 7 8
DTR 1 20 4 3
GPi DCD 7 8 1 2
RI 1
DSR 6 6
TxD+ (none) 6
RxD+ (none) 8
Notes:
- There are two ground pins on the Mac, 4 and 8.
- Both RTS and DTR are wired to pin 1 on the Mac.
- Not all Macs support DCD via pin 7.
- RI and DSR are not supported on the Mac.
- DSR is not supported on the RJ-45.
Credits
This page is all the work of The Mac SE Support pages. I had absolutely no hand to play in it's production. The fine folk put up a web-page, which I was able to unearth after quite some struggle, which is why I copied it instead of plain linking it. I wanted to have a copy of it here, in case the original site moved.
Credits: The Mac SE Support Pages, maintained by Chris Adams, now at http://ccadams.org/se/ earlier at http://home.tiscali.dk/cadams/se/
This page was last updated on: Thu Oct 13 13:17:09 PDT 2005