18 Mar
2012
18 Mar
'12
4:21 a.m.
On 03/18/2012 12:12 AM, Mouse wrote:
Yup, that's the one, and, that's
why it was a bad idea for Sun to use
it as a friggin' console port that will only every do 9600 8/N/1
async ever in its whole life. ;)
Har. The same chip is used for ttyb. And even ttya can have its
parameters changed.
Sure it can. But does anyone run their consoles at anything other
than 9600 8N1? Seriously? And how many people really did lots of
serial I/O on ttyb, in such a way that they actually cared about the
register layouts of the chip?
By the standards of today, or when it was designed thirty years ago?
"Posh" is a great way to put it! The 8530 is a fantastic chip.
Isn't
that the chip Sun used on most of their SPARCstations? If so,
I disagree in at least a few respects. The '8530
is pretty damn friendly to being with, though.
Not nearly as friendly as it could be. Some of it is spazzes which, as
you say, just complicate init code (such as the mapping between the
0xc0 bits of write register 3 and character size). But some of it is
real problems: no FIFO to speak of, a view of hardware flow control
which means either wiring signals up to the `wrong' pins and
compensating in software or disagreeing with almost everybody else
about what signals drive flow control, a weird set of BRG pre-divisors
which impose an unpleasantly low cap on the baudrate if you want
reliable communication, software setting of hardware things like "we're
using a directly-attached crystal to drive the BRG". Perhaps those are
covered by your meaning of "awesome"..
My meaning of "awesome" (though I said "fantastic") is that
I've
designed systems with this chip and it was really, really easy to deal
with and performed extremely well.
It's a descendant of the Z80 SIO, for which the same is true.
How many systems have you designed with it?
-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA