Quote:
It was subsequently discovered that much greater distances could be achieved on ordinary CAT3 UTP cable, as the shielding actually degraded signal quality.
Was it because of the greater capacitance? If greater drive strength is needed to overcome it, multiple drivers could be parallelled. I know that violates the measures put in place for if someone connects two outputs together, but we're no longer talking about consumer and commercial applications, and we techies have enough usderstanding of the situation to avoid such problems, and to fix any damage in the unlikely case that we do mess it up.
Quote:
On the negative side of the coin when distances are stretched: random dataloss, no standards for checksuming or retransmission of lost data... There's something to be said for protocol stacking, and I'm not aware of any standard for character-wise reliable '232. Might be wrong though.
The commercial world no longer has the support for RS-232 that the industrial world has, so we might be on our own as far as doing things like error recovery. I don't really see that as a problem though, as you can just use an oscilloscope to see what the integrity of a signal is at the end of a long cable. There's no need to work in the dark. A nice thing about it is that you can make up your own cables (unlike USB whose connectors are not hobbyist-friendly), with whatever type of cabling suits the need, even doing things like putting large ferrite beads over twisted pairs if desired. Cat-5 cable is used for long runs at 100MHz. Its characteristic impedance is too low to do that with RS-232, but the principle applies, if one wanted to use a different cable.
Edit: Since I just realized I have nearly a thousand feet of cat-5 cable here and nearly another thousand of RG-59, plus spools of 4-conductor cable intended for audio, alarm, remote control, etc., my interest is getting piqued to do some experiments. It won't be today though. Too much work to do.
Quote:
Not so for the parallel port, which I won't shed any tears over...
The only thing I use the parallel port for is my dot-matrix impact printers using fanfold paper which I prefer for program listings. Even this week I'm printing out strips several feet long as I'm developing code, and I don't want page breaks in the middle of program structures. Other times, I want to print just a line or two at a time and see it, without wasting the rest of a page every time. To my knowledge, there is no laser or inkjet printer that can do these things. For printing stuff I get off the web though, the color laser printer I use at the other end of the house is connected by Ethernet.