Hi Brian,
Just watched your video on youtube:
TRS-80 Model 100/102 using teeny and dlplus on Linux
(https://youtu.be/H0xx9cOe97s)
Covers a lot of different stuff, but extremely helpful to my
understanding. I've totally got it straight now about the cabling and
direct connect serial between the modern and the old. Using dlplus with
your mods makes things simple, too.
Thanks for doing it!
Will
On 9/27/22 3:31 PM, Brian K. White wrote:
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.
