Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!rochester!pt.cs.cmu.edu!g.gp.cs.cmu.edu!tgl
From: tgl@g.gp.cs.cmu.edu (Tom Lane)
Newsgroups: comp.sys.mac.hardware
Subject: Re: Deskwriter: serial vs PhoneNet
Summary: You don't need them expensive connectors
Message-ID: <11715@pt.cs.cmu.edu>
Date: 29 Jan 91 16:05:53 GMT
References: <1991Jan25.102811.4724@usenet@scion.CS.ORST.EDU> <1170010@hp-vcd.HP.COM>
Organization: Carnegie-Mellon University, CS/RI
Lines: 35

In article <1170010@hp-vcd.HP.COM>, neff@hp-vcd.HP.COM (Dave Neff) writes:
> [a straight-from-the-horse's-mouth summary of a DeskWriter's performance
>  on serial vs. LocalTalk interfaces; in particular:]
> ... Data that does not compress well
> (full page scanned images are a notable case) can be IO limitted, and
> in that case LocalTalk can be significantly faster than serial.
> If you do print these kinds of images, the speed improvement might
> be worth the cost of the PhoneNet conectors.

Dave's authoritative summary omits one important fact: you don't need to
shell out for those ridiculously expensive LocalTalk connectors if you are
just going to connect one Mac to one printer.  A plain "null modem" RS232
cable will do just fine.  (Your Apple dealer will sell you one if you ask
for an ImageWriter II cable; they're about $10.)

NOTE: for safety with the cheaper cable, you should be sure the Mac and
printer are both plugged into the same power outlet.  The main reason
AppleTalk is so expensive is that there are isolation transformers in the
connectors.  You don't need these if you have only one Mac and one printer
and they are on the same power circuit.

So, assuming you have enough system memory to handle the AppleTalk driver,
by all means switch to AppleTalk.  (I concur with Dave's warning that a 1MB
machine may lose speed with AppleTalk; I don't think the CPU speed is an
issue, however.)

I have not tried this with a DeskWriter, but it works just fine with an
HP LaserJet w/ PostScript.

-- 
				tom lane
Internet: tgl@cs.cmu.edu
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