On Tue, Jun 4, 2019 at 9:45 PM Grant Taylor via cctalk <[email protected]> wrote: > Does anyone have any experience working with modems that didn't include > internal / auto dialers?
Yes. I used to make and sell sync serial protocol engines (COMBOARDs) that often were used to dial up an IBM Mainframe. Sync modems of the 80s often did not have built-in auto-diallers. Here's one we used to use, a Motorola UDS 801 ACU (Automatic Call Unit). http://nwrusa.com/Networking?product_id=17371 https://www.arcelect.com/801_autodialer.PDF I still have one on a shelf in the basement. > I think they were separate devices, which probably means that they > likely had separate serial ports to talk to each of them. Did they > support some sort of pass through? Or did they really require two > serial ports on the host? Yes (though the USD 801 ACU could be controlled by a parallel port _or_ a serial port) In our case, our product had a sync serial port to talk the the Host (implemented with either a COM 5025 or a Z8530). To run the 801 ACU, we soaked up an async port on the VAX as well. Sometime after 1990, I added V.25bis support to our product so we could control autodialers of the day. -ethan
