Mystery IC: Allen Bradley 314B102

Fred Cisin cisin at
Mon Dec 14 18:21:53 CST 2015

On Tue, 15 Dec 2015, Mike Ross wrote:
> Maybe, but Selectrics aren't exactly fast devices; there's a whole lot
> of potential 'no, wait, I'm not ready!' conditions. Would they all be
> ORed onto one pin?

possibly.  It's been done that way before.

> That was my conclusion too. The old Western I/O ads I've seen
> definitely refer to it as having an 'ASCII' or 'parallel' interface.
> Assuming they only ever made the two models; I suppose it *could* be
> some variant of RS232, with very non-standard pinouts - but the ads
> are specific; they made a smart terminal with 6800 CPU & serial
> interface, and a dumb printer with an 'ASCII parallel' interface. And
> that's all I have to go on, beyond prodding the hardware.

REMEMBER, "ASCII parallel" does NOT necessarily mean "centronics-style", 
as was used on TRS80, IBM PC, etc.  "Centronics-style"  was a good system, 
but it was NOT the only one.
"ASCII parallel" could just as easily mean SEVEN bit, with a bit or two in 
each direction for handshaking.   "ASCII" was SEVEN bits, not EIGHT.

> That would be well weird. Still trying to work out what exactly it was
> intended to hook up to; a standard parallel port with a special cable,

There was a time, 35 years ago, when "standard parallel" was an oxymoron.

> leads, 7 lines... I'd expect to see 8 data lines all going to the same
> place if it was anything resembling standard Centronics but with a
> weird pinout. So I'm scratching my head still over just exactly what
> it was supposed to hook up to.

something other than "Centronics"?

More information about the cctalk mailing list