We've been working on and off on a DS1742 replacement, apparently a bunch of Tezros showed up without them as part of some decommissioning process. Somewhere along the way, the fact that the Tezro is a 3.3V system was missed or something, because we certainly didn't realize it! System Source computer museum in Maryland loaned us a Tezro to get the prototypes ironed out though, and now we have a working module!
Despite being a 3.3V part, our replacement is 5V tolerant and can be used with cheap USB programmers like the TL866. It looks like the Tezro will properly kickstart the clock, so you don't have to worry about programming that. Using a TL866 to write data out as a DS1220 works fine. It looks like the original DS1742W 3.3V modules are also 5V tolerant, the datasheet says 6V max on VCC and does not specify if it's for the 5V or 3.3V part. We've successfully read them using a TL866 and a custom in-house device.
Incidentally, this is probably why very few people have had any success with mystery meat DS1742W chips off eBay. Our experience with buying mystery meat Dallas modules is that they're almost always remarked/relabeled counterfeits, and the 5V part appears to be much more common.
Despite being a 3.3V part, our replacement is 5V tolerant and can be used with cheap USB programmers like the TL866. It looks like the Tezro will properly kickstart the clock, so you don't have to worry about programming that. Using a TL866 to write data out as a DS1220 works fine. It looks like the original DS1742W 3.3V modules are also 5V tolerant, the datasheet says 6V max on VCC and does not specify if it's for the 5V or 3.3V part. We've successfully read them using a TL866 and a custom in-house device.
Incidentally, this is probably why very few people have had any success with mystery meat DS1742W chips off eBay. Our experience with buying mystery meat Dallas modules is that they're almost always remarked/relabeled counterfeits, and the 5V part appears to be much more common.