On 9/27/22 14:48, Will Senn wrote:
Hi Brian,
Thanks for the details, it'll take me a while to work through this,
Things have been figured out and added to by by countless people for 40
years, so by now there is just a lot of answer for every question.
but
it sounds believable and achievable. I have purchased one of the ideal
cables you mention. If I understand correctly, the ideal cable should
work fine hooked up between my dell and the m100 because the dell has a
db-9 serial port. My mac on the other hand doesn't so I require a
USB-Serial adapter to make like the Mac has a DB-9 serial port? Then, I
should be able to start talking to the m100 via the ideal cable and
USB-Serial connector plus any gender changer needed between cable and
USB-Serial adapter, right?
No gender changer needed, because that is one of the items that defines
"ideal" in this case. The M100 has a
mostly-normal-but-one-thing-backwards serial port, and the one backwards
thing is the connector is female. So, it's an uncommon combination to
have a 9-25 null-modem cable with a male db25, but they are made and so
it's just a matter of hunting down specific models.
Almost any pc that has a 9-pin com port conforms to a standard that
eventually became standard. Exceptions are very exceptional, like the
Cambridge Z88. Anything else can be counted on. usb-serial adapters come
in both male & female, and you can find special units with weird wiring,
but generally any usb-serial adapter with a male plug is designed to
essentially take the place of the legacy com ports built into old
motherboards.
So, you can consider the 9-pin side the same whether it's a pc with real
com ports of a usb adapter. The only detail left to consider is a
less-important one of the screws vs nuts. By rights any male 9-pin
should have nuts and the cable should have screws, but on this detail a
lot of usb adapters are pretty random. So if you wanty everything nice
you have to actually check the pictures and make sure the adapter you're
looking at has nuts or screws. On that wiki page I listed some choice
usb adapters with everything ideal.
So yes the same serial cable works the same way either to an older pc
with a real com port or a newer pc that needs a usb adapter, which is
again one of the things that defines "ideal" to me.
There are actually bespoke cables you can buy that are usb on one end
and db25 male DCE on the other end which would go right from a pc to a
m100 in one piece, but that cable would be so non-standard that it's no
good for anything else. I prefer keeping the usb part separate, and bog
standard, so it can be replaced later with any other, used for other
things, etc, and the serial cable likewise, even though it is a little
bit special, at least it can be used equally with a usb adapter or
directly to a pc that doesn't need a usb adapter.
If you want to add a 3rd piece, you can get even more bog-standard by
using an ordinary modem cable, which has the right plugs on both ends
but just isn't null-modem wired inside. You can add the null-modem part
in the form of a little 9-pin mini-null-modem. They are no longer as
dirt common as they used to be, but you can still get them. The
advantage to this idea is a 9-25 modem cable is hands down the most
common ubiquitous kind of cable. Not special at all. This places the
extra part in the middle of the cable instead of hanging off the back of
the 100, and is physically pretty small. If you're not using a usb
adapter then it IS hanging off the back of the pc, but at least it's
small and doesn't cause too much stick-out leverage from something
hanging off the port. It's just a little harder finding one that's
male-female instead of male-male or female-female. But they exist and I
think I have link for that arrangement on that page too in the initial
description at the top.
As for the TPDD stuff, once I get the cables sorted out, I will work on
bootstrapping and getting the client on the M100 and a server for my mac.
You'll use the same serial connection for anything/everything regardless
of tpdd, so at least you know you're not wasting any time/effort.
--
bkw
