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z80 CP/M, (circumlunar), 09/17/2018
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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