I've recently acquired a Symmetricom XLi 1510-702 at a price that was too good to pass up. Information seems to be limited, but in the pictures it didn't look too different than any other one I saw. I'm hoping someone on this list might be able to shed some light on the system, but first let me explain. I want to say I've discovered that there are some differences--but given that it's man-made I'll call it undocumented, and nowhere that seems to have much/any information on them. As a quick search will show, there are at least 4 versions of the XLi. There are 1U and 2U variants, and variants with the SAASM equipment (which really seems to just be the connector on the front panel that's wired directly into the Trimble P(Y) capable receiver). But, there are also 4 other variants. If you want a PTP grandmaster, there are XLi models that work with PTPv1, and PTPv2. If you bought one before about 2010, the PTPv1 Grandmaster was still in the 1510-602 part number. However, some time after the PTPv2 version was released, they split that into 4 part numbers: 1510-702, 1510-703, 1510-712, and 1510-713. However, I don't know if the latter two were actually part numbers outside of an ordering system. The 702/703 versions are for PTPv1, and are supposed to come with one or two PTPv1 cards, respectively: part 87-8036. From what I can tell, the firmware on these is very limited, only supporting the GPS module and the PTP card. The 712/713 come with one or two PTPv2 cards, respectively; part 089-00152-000. The two card variants are not to make it a border clock in the PTP sense, but to have it be a master and slave and be able to assess the network PTP performance. Sounds interesting, but I got one with only one PTP card. Now, before I bought it (and before I knew what the 702 model was), I saw that it had the 089-00152-000 PTP card in it, and so I assumed that I might eventually be able to get PTPv2 working. However, after some tinkering, I've found out that the firmware that seems to be loaded on a 702 by default forces the newer PTPv2 card to act like a PTPv1 card. This is somewhat interesting in its own right, because from what I can tell, it's not like PTPv2 hardware is natively backwards compatible with PTPv1. The card itself is mostly labeled inside as a 87-8036 card on the circuit board and connector, but there is an applied label calling out that it is an 089-00152-000. So, I'm not sure if it's the firmware on the CPU card that is forcing it to act as a PTPv1 card, or if the card itself has been flashed. In the manual for the XLi PTPv2 Grandmaster, they do mention multiple partitions accessible via telnet. But, you need to unblock telnet through F135--which doesn't work in this firmware. There does seem to be a breakout for a com port header, which I haven't explored yet. I don't think this was done by the seller--and the MAC address of the PTP port was added on a sticker on the case, so I think it came from the factory this way. But, it makes me think that even the PTPv1 cards can probably be cross-flashed to be PTPv2 cards. However, all of that is a moot point if I don't have the PTPv2 firmware. The firmware is also where things are interesting. I've looked on the Wayback machine, and there don't really seem to be any published firmwares other than what is cataloged on leapsecond.com; and the numbers jump around quite a bit. My firmware on this 702 is at 1.92.2.4. In the archives, there's a 1.91 and a 1.93--but no 1.92. The manual for the PTPv2 Grandmaster seems to hint that there's also a version 2.0-GM. I assume that I can flash my firmware to the last version (2.4), but I think then I'll lose the ability to use the PTP cards. However, I really bought this for a GPSDO and to use as an NTP server... and it doesn't have licenses for PPO or NTP. And, since I don't see a way to dump the firmware, I don't know how I would go back to the current version if I do 'upgrade'. On the plus side, it did come with an OCXO so I'm happy with that, and it seems like it was probably bought as a cold spare (no signs of dust anywhere). However, that last part is also keeping me from buying a CPU card (if I could find one)... because I don't know if a new CPU card would be able to use the OCXO anyways. So, does anyone out there have any experience with the XLi PTP Grandmasters? Anyone have the firmware images for it (specifically, the IEEE 1588 Grandmasters)? Anyone seen anything like this? Am I way off base in all of this? To be honest, I don't really have a use case for PTP but I kind of want to exhaust my options before doing something irreversible, and I figure that this is an appropriate forum for asking (and my apologies if not). -Mike Witt P.S. As an aside, one additional interesting thing about this firmware is that it seems to have PY capability--but it's not usable because it doesn't see a P(Y) capable receiver. I'm not sure if that's just uniform across all of them, but I don't see any documentation on function F92 which is the 'GPS PY FUNCTIONS' menu. Running it just prints the message 'GPS SAASM AVAILABILITY/NOT AVAILABLE'