Serial interfaces (was Re: Any former Psion 5 owners out there?)
ard at p850ug1.demon.co.uk
Tue Jul 20 14:46:08 CDT 2010
> On 7/19/10, Liam Proven <lproven at gmail.com> wrote:
> > I am very happy to say that I have not used a serial port for anything
> > in a good 2-3y now, and not for anything more than a very occasional
> > sync of my Psion 7book...
> I use serial ports every week.
Every week? I use them every day..
> > I really hate RS232. It is the most troublesome interface of any kind
> > on any computer I've ever used. I celebrate its disappearance with joy
> > and I hope never to have to use such a port again. All the crap with
> > baud rates, stop bits, parity bits, flow control and all that hateful
> > 1960s-ish nonsense is just a fading memory now and I hope I never have
> > to refresh it.
> It may be hateful 1960s nonsense, but if you know how it works,
> presuming you have the ability to control all the parameters of one
> end of a connection (software-controlled params, jumpers, straps,
> solder bumps, etc), you can still take something made in 1968 and
> attach it to something made in 2008.
I must have well over 100 machiens with RS232 ports here. And I've never
had any real porblems getting any pair of them to talk to each other. OK,
IO have to read the fine manuals, I have to set some swiches, I may
haveto make a cable, but that's it. it will work. My 1970 Philips P850
will talk to my 2000 HP49G. My HP9830/11205 interface will talk to my
TRS-80 M100. And so on.
> > Apple did serial ports right on the Mac. You plugged things in, they
> > worked, thankyou and goodnight.
> Mac-designed things, sure, but Apple didn't make it easy to talk to
> the world full of "standard" serial devices (of which there were
> *lots* in the 1980s).
You said it a lot more politely than I would ahve done.
But to be fair, there were generally few problems if you stuck to machine
and peripherals from the same manufacturer anyway. If you bought an HP
desktop machien (say an HP120 CP/M machine or an HP150 tocuhscreen PC)
and an HP seiral printer, then one of the manuals would tell you which HP
cable to buy to link them (you did get wirelists if yuou wanted to make
your own..) how to set the switches on the printer and how to configure
thesetup screens on the computer. Do it just as they said and it worked.
> > I really like USB.
> I really do not like USB. It takes hundreds of cycles and more to
> move a simple message, it's a host-based, not bi-directional design,
> and it's only available on somewhat newish kit.
Basically my problems wit hit too. It's not summetrical ('host based'),
it's over-complicated, and it's not available on anything I own.
> The host-based aspect of it is probably my biggest peeve - with a
> serial port, it's just TxD, RxD and perhaps some handshaking lines
> (more likely in the past, but sometimes supported in recent products).
> What that means to me is that I can buy a device that might be
> intended as a client (a Palm Pilot, to give a specific and handy
> example) and by dropping an app on it, turn what was manufactured to
> be a "receptive" device into an "active" device - such as use it as a
> VT100 replacement for configuring Cisco routers (boy my boss's eyes
> bugged out when I pulled a Palm out of my pocket, clicked in a serial
> cable and fixed something in seconds instead of leaving the room,
> retrieving a laptop, setting it up, etc., etc.)
Which is where we came in, the idea of a palmtop machine that could be
used as a terminal.
> A USB-equipped Palm is meant to be addressed as a 'peripheral' and
> cannot be a 'host' - that limits its usefulness to me.
Makes it useless for me :-)
> It has some advantages - power for light-duty peripherals is great,
> simple connectors is great, not having to worry about DCE and DTE
> orientation is handy. It's great for mice and keyboards, sure, but
> I'm less convinced about higher-bandwidth uses.
Since it's not symmetirc, there are the equivalents of DTEs (host
computers0 and DCEs (peripherals) in USB. The big differnece is that with
RS232 you can make a null-modem adapter to connect 2 DTes or 2 DCEs, it's
just a matter ot wiring up a coule of sockets. You can't do that with USB.
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