Synchronous Modem Eliminators

Hi, All, I've been discussing 1980s and 1990s IBM gear with a list member via PM, and the need for modem eliminators has come up as a topic. I have worked with a variety of older Black Box units back in the days when I used Bisync comms every day, but looking around now, I see no EIA/RS-232 units for sale on eBay and other places - it's all V.35 (at multi-megabit speeds for CSU/DSU) and RS-422 and RS-530 (RS-422 on a DB25). 25 years ago, it was common to want to attach sync devices between 1200 and 56Kbps via RS-232 but not so much any more. It's not hard to make a Sync Modem Eliminator - in its simplest form, it's going to look at lot like an async null modem cable/box, but with active clocking (normally generated by the DCE) on pins 15 and 17 on both DB25s. There used to be a lot of baud rate generator chips, but for a small range of speeds, a properly-sized crystal on a 4060 clock/counter chip, perhaps a D-flip-flop used as a divide-by-2 (to square up the waveform and to shift which baud rate is "missing" because one stage of the 4060 chain is not brought out to a pin), and a 1488 to drive the clock to the DTE hardware. Where it starts to get complicated is that commercial RS-232 SMEs also had options to strap carrier detect and RTS/CTS, optional CTS turnaround delays and more. There were lots of jumpers and configuration often took some experimentation for a new set of devices. My question is, for those reading this that still use sync serial, is it "worth" designing and sharing a simple SME that might not have all the bells and whistles and user-configurable options, or is it "worth" just keeping the design very simple (3 chips plus a multi-voltage PSU, or multiple chips and a single-voltage PSU) and acknowledging that it will only work for 80% of the cases out there? It is, of course, easier to purchase than build, and there were once large quantities of the "right device", but I think as comms speeds have risen, not that many of these low-speed devices have survived, and certainly nobody is attempting to empty a warehouse of them at the moment. It's also entirely possible that the demand for synchronous serial comms over RS-232 lines is so small that the entire roster of interested parties would fit on a very short bus, so please chime in if you still use sync serial below 64kbps for anything. I'm curious to know who does and what devices they have. -ethan