------------------------------------------------------------
           z80 CP/M, (circumlunar), 09/17/2018
------------------------------------------------------------
I know  that at  least one  person is  OK with  me yammering
about z80 CP/M stuff on here, and so I continue[1]!

I've been trying  to connect my z80  to my Pi, so  I can use
the wifi on  the PI to connect my z80  to the wide world[2].
Everything  is connected  up physically  (I need  to post  a
picture I suppose), but I'm having communication issues...

If I open up minicom on the pi, and kermit on the z80, I can
type  gibberish  back  and  forth. Not  real  useful.  Tried
different baud rates, flow control, etc. to no avail.

When you boot the Grant  Searle z80 CP/M system, the monitor
waits for a space from either  serial port so it knows which
to  use as  the console.  This is  working from  both serial
ports;  that is  to say,  the message  is displayed  on both
screens, you can  hit space on either port, and  it works as
the main console.

The serial  setup in  CP/M is managed  with the  IOBYTE, and
Grant has set it up to  work perfectly on his CP/M BIOS. One
thing that  means is that you  can POKE 03h with  mbasic and
change the  serial configuration  at any  time. It  is quite
easy, in fact, to change  the console output between the two
serial  ports  while  the  system  is  running...  and  that
functions properly.

Here's where  things get  interesting. If  I do  POKE things
back  and  forth  between  the two  serial  ports  (with  my
laptop/minicom on  one port, and my  pi/minicom on another),
and THEN  try connecting via  kermit, I get legible  text. I
can type  back and forth  between the two and  everything is
clear.

After the POKEing,  I can start agetty on the  Pi, and login
via kermit  (I need  a better  OR simpler  TERMinal program,
that is in the works.) There is a bit of a buffer issue, but
it works  fairly well. I even  used SSH through the  PI that
way and  logged into  grex... though,  the buffer  thing (it
seems to be  waiting for a CR to send  all the text through)
makes it somewhat unusable. Nothing gets lost that is typed,
but you can't see what you're typing until you press enter.

So, I feel like I have  two issues... one; why is the serial
port  not working  unless I  POKE  things? and,  two; can  I
perhaps get  or make  a terminal program  that isn't  in the
way?

I should  probably put  this out, in  case anyone  in gopher
space is a z80 assembler person  and has the time and desire
to lend a hand: there  is a TERM.ASM, basic terminal program
that is  actively developed  for the  RC2014 z80  SBC, which
would  solve my  problems[3].  It is,  however, written  for
slightly different  hardware. I  haven't emailed  the author
yet- I  suppose I should  try, as  they would likely  be the
best suited to help me :)


[1] gopher://circumlunar.space:70/0/~yargo/clog/zi-stalling-projects.txt
[2] gopher://sdf.org:70/0/users/tfurrows/phlog/2018/afn_z80modem.txt
[3] https://github.com/maccasoft/z80-apps