Hamby wrote on 2020-10-04, 18:24:

I haven't done anything with them yet, but awhile back I got a Radio Shack CGP-115 plotter and more recently a Tandy DMP-100 pri […]
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I haven't done anything with them yet, but awhile back I got a Radio Shack CGP-115 plotter and more recently a Tandy DMP-100 printer.

I was doing a bit of unrelated research on building Tandy 1000HX printer cable, when I read that connecting "newer" PCs to older Tandy printers can damage the computers.
I was planning on connecting the printers to my K62-300 Win98SE PC, and/or my old Toshiba T5200 laptop.

I even considered connecting them to my modern PCs using a USB to centronics adapter cable.

Can anybody tell me how much, if any, danger my computers are in if I connect them to these printers?
Is there an interface I can build that would protect them, if so?

I hate thinking my Tandy 1000HX is the only machine with which I can play with them.

AFAIK, the printer port edge style connector on the Tandy 1000 series still went by the Centronics standard. Tandy printer cables still worked with non-Tandy printers. It was just that edge style connector that was different and I also believe the printer port was not bidirectional. All the Tandy printers I ever used had a standard Centronics connector on them. I honestly don't think you are going to do any damage by hooking up a Tandy printer to newer computer. If you need a definitive answer, I suggest posting the question on the Tandy section of the Vintage Computer Federation forum. There are many Tandy specialists there who can give you a better answer than I can.

I've been looking to see more info on the Tandy parallel ports, and came across a couple more mentions that older printers were wired differently.

I finally found this PDF of the DMP-100 printer manual.

On page 10/22 it has a table of the pinouts for the parallel port.
https://colorcomputerarchive.com/repo/D ... Tandy).pdf

I'm trying to compare and see if the DMP-100 is one of the printers with non-standard pinouts.

Here's a video of a guy trying to connect his Radio Shack DMP-105 to an IBM PS/2... and he claims he has to cut pin 18 on the printer cable.
According to that DMP-100 PDF... pin-18 on the printer supplies +5 volts.

I do wonder if using a centronics to USB cable would bypass this issue? I have a short one of those I used to connect to my Cannon BJC-80. At least it would allow me to connect my modern desktop to the printer... 😒