Grex Hardware Conference

View Responses

Grex Hardware Item 121: Port Juggler (TM) by Momentum Inc.
Entered by rcurl on Sun Dec 8 02:56:14 UTC 1996:

My new PowerMac, like all Macs, came with a printer port and a modem port. 
But I have a modem, AppleTalk network, and a serial printer. An item in
the catalogs seemed to be the thing to increase the number of serial
ports, called a Port Juggler, by Momentum Inc (of Hawaii). I took the
'flyer' and ordered it. When I tried to set it up it seemed to crash my
system, but it turned out that was the Mac itself. Now I have the Port
Juggler in business, and (so far) it seems to be doing its things, which
are: 

I put my modem on the Mac modem port, because the Port Juggler interrupts
PPP connections. Well, that's one negative.
 
I put the Port Juggler on the printer port. That provides four (4) ports,
one of which is the default and the others "juggle". On Momentum's
suggestion, I put the AppleTalk network on PJ#1 and a serial (Color
Stylewriter) on PJ#23. The AppleTalk network includes a DeskWriter printer
(with AppleTalk interface) and another Mac (PowerBook). 

What happens, then, is if I select the Stylewriter to print, AppleTalk is
turned off automatically and the port is "juggled" to PJ#2. If I want to
use AppleTalk for file transfer or the DeskWriter, I select one of those
in the Chooser, and AppleTalk is reenabled, and the printer port is
juggled back to PJ#1. 

The "acid test", so far, is when I took the same document and printed it
in rapid succession to both printers. I started with the DeskWriter. The
document was scrolled for background printing, when I printed it also to
the Stylewriter. The Deskwriter finished its job, the PJ "juggled", and up
came the Stylewriter to print its job.

AppleShare is a little one-directional. I can have File-Sharing on in the
remote PowerBook. However if I turn on File-Sharing in the PowerMac, I
can't juggle for local printing on the Stylewriter - the PJ#1 holds on
AppleShare (reasonably enough, so it is always accessible remote, though
limiting local printing). Well, can't have *everything*. 

Anyway, I still have three (3) free serial ports. So, what can I put on
them?

8 responses total.

#1 of 8 by rcurl on Sun Dec 8 07:00:20 1996:

Addenda:

It is the POWER Port Juggler, with PowerMac native code. 

It does not work with GX drivers (I had installed GX drivers because they
sounded like "good things" from what little I could find about them).

And - ah hah! caught you all! how unobservant! - I still have two (2)
serial ports!

#2 of 8 by ajax on Sun Dec 8 22:34:35 1996:

  Two more ports to fill up?  Let's see...I'd probably add an X-10
controller ($70) and a Color QuickCam ($200).  Of course, if you get
another port juggler, that will give three more, in which case I'd
suggest a LabelWriter ($200), brain wave monitor ($1,000), and full-
body 3D digitizer ($165,000).  Beyond that, you'd just be adding
frivolous peripherals.  Though a serial-output GPS receiver ($400)
would be useful for alerting you that someone is stealing your house 
while you're computing.  Can you add port jugglers to juggled ports?

#3 of 8 by rcurl on Mon Dec 9 07:00:39 1996:

No, you can't daisy-chain Power Port Jugglers. However, you can have one
on each Mac port, giving eight (8) ports. One of the PPJ ports is the
"default" port - you might call it the straight-through port. The other
three are juggled from PPJ#1. The unit always drops back to PPJ#1 when the
others are not being actively used. 

Well, yes, you can pile on all those goodies. I will probably connect my
GPS for use with APRS, when I get a better external antenna. If I move my
X-10 system from the old Zenith "XT", that would be another port. 
Incidentally, there was a spate of discussion - or uproar - a short while
back on various Mac discussion web sites, about the PJ. Some people were
very unhappy - some even saying it was ruining their cables. Some said
they were installing A/B switches instead. Certainly cheaper, but I'm not
sure about the wisdom of switching active AppleTalk ports, and even just
serial ports, while the machine is on. In any case, A/B switches will not
let you queue printer output to two printers. 

I gave the PPJ a semi-acid test by alternatively printing a document to
the Deskwriter on the AT network and the serial Stylewriter. I quickly
printed it to, in sequence, the SW, DW and SW (i.e., scrolling the job to
background). What it did was tackle the two queued printjobs to the SW
first, and then juggled the port to do the DW printing. I was impressed.

[I was doing this from an Excel 5.0 document, and also doing Save As'es
simultaneously, because that sequence had bombed the system when I was
trying to use the GX drivers - but no problem with just QuickDraw
drivers.]

I also opened an AppleShare connection to the PowerBook. With that on the
desktop, it would not juggle to the serial printer. You don't really get
two, independent, new serial ports - only one can be open at a time.  When
I tried to print to the SW, I got a dialogue saying that the port was busy
and to close the application (AppleShare) in order to print. When I did
close it, the printjob then printed from the queue.

The PPJ is not cheap and, even for what it does, you might call it rather
pricey. However the convenience is great, not having to shut things down
to change peripherals, and besides I had just bought the PowerMac 7200
system, so what's another 5%? That's less than the taxes.

#4 of 8 by n8nxf on Tue Dec 10 15:22:08 1996:

I juggle my own ports.  Just plug and unplug as required.  Perhaps I'll
get one of those fancy, manual, 4 way switch boxes some day.  Easy to
install and I don't think I'll have to open the manual to figure out how
to use it ;)

#5 of 8 by rcurl on Tue Dec 10 15:35:53 1996:

All the manuals say to turn off the computer when changing what is plugged
into the serial ports. I didn't do that when I had my SE networked to an
AppleTalk networ or serially to an XT, and never had any trouble. But
anyway, its a pain getting behind my machines to shift cables and, as I
said, you can't queue print jobs to two different printer and go away
while they print, with A/B boxes. [Honestly, Klaus, it isn't fair making
me justify collecting gadgets..... ]

#6 of 8 by n8nxf on Tue Dec 10 22:00:14 1996:

[You don't need to justify it Rane.  We all need stuff to do ;]

#7 of 8 by gull on Wed Dec 11 00:04:58 1996:

Is it true that A/B switch boxes can damage printers?

#8 of 8 by rcurl on Wed Dec 11 07:00:58 1996:

I doubt that, but you can interrupt processes which might crash programs.
The only problems I had otherwise is having the system not recognize a
peripheral if it isn't switched "on" on bootup. Maybe the problem with
switching cables when the system is "hot" is the possibility of forming ground
loops that might damage something.

Response not possible - You must register and login before posting.