Re: Oldworld Serial Console
On Fri, Sep 24, 2004 at 03:03:14AM -0400, Rick Thomas wrote:
} On Friday, September 24, 2004, at 02:08 AM, Brad Boyer wrote:
} >I haven't tried it on ppc, but I use it on 68k macs sometimes. I usually
} >use ZTerm on another mac and a standard mac printer cable for the
} >connection.
}
} Don't you need a null-modem cable? Or is there something I don't
} know about the old Apple serial interface printers? (Like -- do
} they present a DTE-like interface, so *all* printer cables are
} essentially null-modem cables? That would explain why my Mac guru
} friend just happened to have some lying around and was so willing
} to loan one to me... <-8)
Consider what a serial line is designed to be. Basically, it is intended to
connect a host to a device, or a host to a peer. When a host is connecting
to a device (e.g. modem, most terminals) it makes sense for the device to
accepts writes on the write pin and reads do its own writing to the read
pin, because it knows it is connecting to a host. When two peers are
connected, however, both expect that they should treat the connection as if
to a device, thus it is necessary to swap the read and write wires. Now,
for purposes of what it means to be a device or a peer, printers are peers.
No, I'm not sure why this is, but it is how things have historically been
done. This means that, yes, a serial printer cable is a null-modem cable.
In fact, I can attest to using an ordinary Mac printer cable between my
Oldworld Mac running Linux and my dual G4 with a Keyspan adapter and
running MacOS X. I use minicom on the Mac and have set up quik, not BootX,
to allow me to have a console over the serial line.
} Rick
--Greg
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