22 Jan
2014
22 Jan
'14
5:55 p.m.
On 01/22/2014 05:04 PM, Eric Smith wrote:
The NEC uPD7201(A) and Intel 8274 have a misfeature
that makes them almost
unusable with modems that employ synchronous modulation (which is almost
all common PSTN modems at bit rates of 1200 bps or higher, except bell 202
and V.23), except when an error control (e.g. MNP or V.42) used between the
modems and flow control is used between the modem and the 7201/8274.
I've put Z80 SIO/DART and 8274 chips in real production products.
They're similar, but obviously not identical. However, if you've
programmed one, you'd be right at home with the other.
That being said, I've never used one in synchronous mode. For that,
I've always used 8251A or 2651/2661 chips, with a preference for that
latter.
--Chuck