Wiring up an LPFK

Hi, All, Years after we were discussing the LPFK in detail, I have managed to be home long enough to find mine and hook them up. I've also dug into the innards a little bit to understand how to wire up a cable, and it brings me to a question... what is pin 4? According to the old discussions, pin 4 was described as +5V or "+5V through a pullup" since there was clearly not a direct path from pin 3 to pin 4. My tracing of the board shows me that pin 3 is indeed +5V in, but pin 4 is connected to +5V through a signal diode, *and* to ground through a diode, *and* (through a small resistor) to both inputs on one of the gates in the 74LS00 whose output is RESET. So... it looks like a diode-clamped input for resetting the 8031. My question is, given that one diode drop is 0.7V (I don't think these are zeners, at least they are in orange glass packages with a yellow stripe, not a silver package with black stripe and numbers like the zeners I recognize), can you safely put more than 6V on this input or not? i.e., is it meant to be connected to RTS or DTR so that the host can easily reset it? I know more modern serial ports (those without 1488s and 1489s, for instance) don't often hit +/-12V, but I know nothing about what the LPFK was supposed to connect to, so I can't guess what serial voltages the LPFK would have to accommodate. Does anyone have a pinout or a good description of the original IBM cable? To connect up my LPFKs, I bisected an old 8-pin DIN cable and added a DE9, and for the interface, hacked a Keyspan-brand RS-232 dongle to sever RI from pin 9 and to bring up +5V from the USB connector. I've seen other serial devices (like those used with a POS) that have power-over-serial on pin 9, so I know it was commonly done for embedded devices, but I can't seem to find a good name for the practice (I was planning on marking altered devices with "P9" so I know that pin 9 is powered. It's fun finally getting some practical experience on the real hardware and to see the sample code I wrote five years ago for Phil Pemberton's library in action. Thanks for any info, -ethan