[C64] Garbage characters when using UP2400

tschak909 / platoterm64

PLATOTerm for the Commodore 64

GNU General Public License v3.0

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[C64] Garbage characters when using UP2400 #37

Closed rhalkyard closed 4 years ago

rhalkyard commented 4 years ago

I've noticed that when using the UP2400 driver, screens will often have garbage characters in places, and incorrectly-drawn or positioned, or sometimes completely missing elements - see the screenshot below.

This doesn't seem to be a protocol-decoding issue, since the same screens render fine with SwiftLink, but they always seem to render with the same corruption under UP2400. Could this be related to #28, discussing a change in the upstream UP2400 driver to fix an issue where 0x00 bytes got received as 0x0D? From commit f270f520a, it looks like the the UP2400 driver distributed with PlatoTerm has diverged from that codebase, but I couldn't find a copy of the source to examine the changes.

vice-screen-201909181346

tschak909 commented 4 years ago

I haven't made any changes to up2400 from its original repo. -Thom

tschak909 commented 4 years ago

it is important that RTS/CTS handshaking be set up, also, the modem needs to not escape 0xFF as 0xFF 0xFF (treat as raw).

rhalkyard commented 4 years ago

Thanks; I'll double-check. I've only been able to try this under emulation with tcpser, since my homebuilt wifi modem is unreliable garbage (which in turn is my motivation for #31 😄). I've tried tcpser's various flow-control options, but the VICE docs are incredibly unclear as to how RTS/CTS works with all that.

Looks like the UP2400 driver change was committed by @greg-king5 in f270f52

commit f270f520a8320c670188908d670fb489340e1bb5
Author: Greg King <gregdk@users.sf.net>
Date:   Fri Dec 14 00:01:03 2018 -0500

    Replaced Johan's ser-up2400 driver with one that has several fixes.

    * Puts the buffers in a safe place.
    * Stops and closes the RS-232 device when requested to do so.
    * Has some less complicated code.

tschak909 commented 4 years ago

If you use tcpser, PLEASE USE MY FORK, which has the IAC escaping code excised:

http://github.com/tschak909/tcpser

and run tcpser with -i "&K3"

-Thom

rhalkyard commented 4 years ago

That seems to have done the trick, thanks!

Seems that these days everyone has their own tcpser fork! It's hard to keep track of all of them!

greg-king5 commented 4 years ago

Three points about VICE:

The current version of VICE can be told to handle the IAC escapes properly (it's called "IP232" there).
The user port emulation doesn't, yet, connect the handshaking lines to programs.
VICE can connect directly to the Internet; it doesn't need to go through tcpser. You can put Irata.online's URL into VICE's RS232 settings as a "device" name. Then, Platoterm will connect as soon as it starts (no need to dial it).