serial upload from lc575

5 replies [Last post]
Joined: Oct 7 2004
Posts: 3

Mum's tired old LC575, running system 7.5, has a broken floppy drive and a broken modem, and she wants me to get a few hundred pages of typed text off it.

I am trying to make a serial connection to my PC, using the parellel port - Clarisworks looks like it can do it, making a serial connection through the parallel port, and using the Xmodem transfer protocol... but everytime I connect up the serial cable, the Mac freezes.

With hardware I'm not really sure what I'm doing, I have tried a 25pin - 9 pin serial cable, and also a serial to parallel converter device - both make the Mac freeze.

I looked at the voltages on the Mac's parallel port, they seem to be all around 2.8V - maybe this is the problem as RS232 should be +/-10V...

Does anyone know the simplest solution here?


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Jon's picture
Joined: Dec 20 2003
Posts: 2804
The Mac printer port is not a

The Mac printer port is not a parallel port, it is serial. You will have to use a null modem adapter and a serial cable to the PC. Or, if you happen to know where to find one easily you might be able to stick in an LC PDS ethernet card. I'd check that there are the ethernet drivers already installed first though.

But, the Mac definatly can't go printer port -> PC parallel port any easier that it is to just do it over serial.


I am not in this world to live up to other people's expectations, nor do I feel that the world must live up to mine. - Fritz Perls

Joined: Oct 7 2004
Posts: 3
Still a bit confused...

Mac printer port - you mean with the DB25? That's what I was referring to. I am trying to use it as a serial port, connecting to the serial port on my PC, but with the serial cable that I got it makes the mac freeze when I plug it in.

I have a serial cable 25pin one end 9 pin the other, should I connect that to a null modem cable then to my PC serial port?

Are the voltages the same? I couldn't find +/-10V on the 25pin D connector on the mac.

Eudimorphodon's picture
Joined: Dec 21 2003
Posts: 1204
Re: Still a bit confused...

nickn wrote:

Mac printer port - you mean with the DB25? That's what I was referring to.

There's your problem. That 25 pin port on the back of the Macintosh isn't a parallel *or* a serial port. It's a SCSI port. For hard disks and whatnot.

The Mac's serial ports are the small round ones that look like PS/2 keyboard ports. (Like the port the keyboard plugs into, but different pinout.)


Joined: Oct 7 2004
Posts: 3
RS232 then?

Ah, ok, thanks.

So is the Mac serial port RS232 standard? Do I just need an adapter plug?

-Wallstreet-'s picture
Joined: Dec 26 2003
Posts: 148



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