MITS 2SIO serial chip?

From: Peter C. Wallace <pcw_at_mesanet.com>
Date: Tue Dec 18 00:33:13 2001

> >
> ...and you have to generate an address strobe,

Wrong! The ISA bus is not multiplexed (well for I/O anyway) the 8250
adress strobe is simple grounded

 and you have to deal with the
> setup and hold time issues,

Wrong! Easily met with 4.77 or 8 Mhz bus speed

which the bus doesn't.



  ... pretty much the same as
> any other device costing a third as much. Of course it depends on whether
> you're satisfied with "getting by" or would prefer to meet the spec's.

8250 meets the bus specs no problem...

> >
> > Just because YOU don't like
> <snip>
> > > I had to buy 8250's to populate multi-port serial boards for various S-100
> > > systems back then and was acutely aware of the cost of an 8250 as opposed to
> a
> > > less generously provisioned device. It had lots of parallel bits, that some
> > > folks used, but I never needed them.
> >
> > I pressume thats why IBM chose it since it supported a full set of Modem
> > control lines...
> >
> That would be a reason all right, though the 2681 had about as many, IIRC.
> >
> That's not what the extra parallel port bits did, is it? I thought the
> handshakes were still automatic. ... I've not had to hook up a serial device for
> so long I can't remember the specifics. <sigh> Oh well... we always tie the
> cable back to handshake with itself anyway, and rely on the X-on/X-off protocol
> ...
> >
> <snip>
>
>

Peter Wallace
Mesa Electronics
Received on Tue Dec 18 2001 - 00:33:13 GMT