Does anyone know anything about the HP13264 Data Link Interface, or the network (?) it was connected to? It's mentioned in passing in the documentation for the HP98268 comms card, and I've just bought one. Let me describe ehat I've discovered so far. Physically it's a plastic box of the same design as used for many other HP intefaces (like the 82164 HPIL-RS232 interface). 2 cables come out of it. One ends in a 50 pin Microribbon plug, which is the HP 'RS232' port connector. The other is a figure-of-8 cable ending in a strange 6-contact plug that I'll describe more later. On top are 2 LEDs marked 'Link' and 'Transmit'. Inside there's a PCB containg a few standard chips, some passives, and 2 optoisolators (one single, one dual). It draws power -- +5V, +12V, -12V from the HP RS232 port (power lines were provided on this connector). The only RS232 signals used are TxD, RxD and RTTS (which is strapped to CTS). The last is used as a transmit enable. There's an isolated PSU on the PCB, driven by a 555 astable. It provides 6.7V to the circuity on the 'network side' of the optoisolators. The TxD and RTS signals are bufferd to TTL levels (1489 chip), and fed into the dual optoisolator. The RTS signal also drives the 'Transmit' LED. On the other side of the optoisolators, they go to 4011 NAND gates, which drive 4 transitors as a full-H driver. These drive the netowrk cable (there are 3 siganls on this cable -- Sh (Shield) which is connected to the ground of the isolated PSU, and +, - which are driven by this full-H circuit). The network cable is monitoed by a 311 comparator. Its output drives the remaining optoisolator, the output of which is buffered to RS232 levels (1488) and then drives the RxD signal to the computer. This optoisolator also drives a circuit that controls the 'Link' LED, such that a '1' on the network cable flashes said LED. If the network cable is in a steady state (no matter what state), the LED is off. Note that the receiver is always enabled, a computer monitors its own trasmission. Presumably that's used for collision detection. There are 2 3-way terminal blocks on the PCB for the cable to the network connector. Corresponding terminals are linked by PCB tracks. The cable is a figure-of-8 thing with each part being a screend (twisted?) pair. Obviously the inners go to the '+' and '-' terminals on the PCB. This cable ends in a connector that's a bit like an overgrown microribbon connector without the outer hosuing, but with only 6 contacts. There's a picture of the interface and this connector on the Austrralian HP museum site. The 'business end' looks a bit like this : - | | -==--==--==-- | | | -==--==--==-- | | | - Where == is a contact area (6 in all) That would be looking at the face of the socket, which must have a 'T' shapped cutout in it to allow the plug to go in. I assume there are6 contact springs in the socekt to connect otther cotnact areas on the plug. Now, corresponding cotacts on the 2 sides of the plug are connected together. But not directly inside the plug, but rather from one side of the plug, up one of thr pairs of the figure-of-8 cable, then via PCB tracks to the corresponding wire in the other pair, back down the cable, and to the contact on the other side of the plug. This means that the figure of 8 cable won't appears as a 'stub' on the main cable. I would guess that the socket has contacts that touch when the plug is removed, thus completing the connections I've just mentioend. This looks a bit likea French teleohone socket, but I'd heard that this was normally an 8 pin device, withe the other contacts on the 'head of the T (right hand part of my diagram). Whether I could use such a socket andwhether it would need modification I don't know. I also don't know if such sockets nroammly short corresponding contacts on the 2 sides if no plug is connected (as I mentioned in the last paragraph, this would be desireable here). So, does anyone know anything about this device? What was it used for? What was it used with? What was the socket? Protocol? Any manuals/docs o the web (a google search found nothing useful)? Thanks in advance for any help -tony