On Wed, 7 Oct 2020, Al Kossow via cctalk wrote:
Synchronous
serial lines are not typically a feature in the sort of
machines people are likely to be running something like Simh on,
especially laptops. I'm sure there were Sync serial cards for ISA but
probably not anything more recent.
you could get PCI V.35 cards
https://www.ebay.com/itm/Barr-Systems-291456-Sync-Max-PCI-Rev-1-Card/264317…
Umm, PCI has become almost as legacy as ISA, but here's the first link:
<https://www.farsite.com/synchronous_X.21_RS422_V.35_RS530_PCI_PCIe_cards/farsync_t4ee_pcie_synchronous_card.shtml>.
that came up with "PCIe HDLC" popped into a web search engine.
If you were so inclined, you could probably wire it to a contemporary x86
laptop via one of those Thunderbolt-to-PCIe thingies (for the record: I've
had one of my older x86 laptops put on FDDI via a similar arrangement with
a PCIe-PCI bridge wired via the docking station, and could do the same
right away with my most recent one and its ExpressCard interface).
FWIW,
Maciej