MITS 2SIO serial chip? - test-drb@ccmp.vtda.org

20 Dec 2001

---- On Fri, 14 Dec 2001, Allison
(ajp166(a)bellatlantic.net) wrote:
...
  8251 was an OK chip, it had bugs, FYI there are
three versions
...
  and each has it's oddities!   I have tons of
them and use them
...
  but, you do have to be aware of the oddities.
The worst ones
...
  are initial programming after reset (buffer
clear bug) and the
...
  repeats last character on /cts false if TX
shifter is not empty
...
  (8251A).  However the 2SIO didn't use it.
 NS* did use them as did many others.  The worst chip was
...
  the 8250.
 Allison 
IIRC the Intel 8251 did full Sync as well as
Async which was a plus.  It's annoying
drawback -- (DEC used it in the Robin and
Rainbow) was the lack of modem flow control
support.
I'd have killed for an 8251 with
CTS/RTS/DSR/DTR and DCD all on chip.
Perhaps it should've been done on two chips
if Intel couldn't get it on one.
Bill