The future of our hobby (was Re: ImageDisk project is canceled)
ard at p850ug1.demon.co.uk
Thu Dec 29 17:15:13 CST 2005
> Tony Duell wrote:
> > Note for the uninitiated. The IBM serial card has 2 odd features that
> >were not present in most, if not all, clones. The first is that it can
> >pull pin B8 (IIRS) low during I/O reads, needed if the card is used in
> >slot 8 of the IBM PC/XT. The second is that it has a current loop
> >interface as well as RS232 .
> Does any of the newer serial cards have the current loop option?
I believe there have been current loop cards for PCs (the current loop
interface was used industrially, and no I am not thinking of the
_analogue_ current loop used for industrial sensors)). But I've not seen
a combined RS232 and current loop card for a PC other than the original
> Was it only TTY's that used the current loop?
Oh no. A lot of serial terminals did (DECwriters, HP terminals, etc. IIRC
the serial interface for the HP9825 series could do current loop (maybe
the one for the 80 series to). Somewhere I have a couple of control
interfaces that are current loop on the host side. I am alos pretty sure
I've seem a modem with a current loop interface on it. And of course most
minicomputers had current loop interfaces (if only to link to teletypes).
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