15 Dec
2012
15 Dec
'12
2:47 p.m.
On Dec 15, 2012, at 5:36 PM, Mouse wrote:
None of the UART chips I am (even vaguely) familiar
with, like the
8530, fit this description. However, a serial line such as the VAX
uses is not a complicated device; I could probably put one together
from discrete logic in no more than an hour or two. It could very well
be just a small section of one of the custom chips involved.
Well, the 8530 is a bit of an oddball amongst UARTs. The PDP-11
standard console SLU is extremely simple and doesn't even provide
any real buffering; my assumption from its design is that it's
meant to be implemented with minimal hardware and used with
minimal software (e.g. ODT, which is generally implemented in the
microcode). I imagine the VAX, which is very much a spiritual
descendant of the PDP-11, would use basically the same hardware
(if it ain't broke, don't fix it).
- Dave