> John Payson <supercat@MCS.NET> wrote:
> > [2] Are there any 16C74's out there where writing a character to the serial
> >     port would risk "reading" one?  If so, but this quirk has been changed,
> >     when did this change come about?
>
> The UART has separate Rx and Tx regs, probably because they discovered the
> MOVWF problem very early on.  Too bad they didn't think to do the same for
> the parallel host port.  Although that still would have left the RETURN
> problem.

True, though Microchip has indicated that they've fixed that too in new
silicon.  IMHO, the host port as Microchip implements it is still somewhat
limitted, however, since there is no good way to distinguish commands from
data without adding more external logic.  Think what you like about the
8042's instruction set, but having two read addresses and two write addresses
from the host's point of view can really improve things a lot.