I recall seeing recently an asm listing on how to twiddle with the rs232
on the m100/102/200 but I can't recall where I saw it or find it in my
browser history. Does anyone know what i'm talking about and know where
to find it?
-Russell
On 10/6/2019 11:40 AM, Russell Davis wrote:
Thanks for doing that.
while trying to workout what was going on I stumbled across
https://www.web8201.net/files/LIBRARY_web8201/M100SIG/Lib-10-Tandy200/NULMDM.200
which said tie the RTS/CTS together for the T200 which seems to be
what you worked out.
-Russell
On 10/6/2019 10:47 AM, Kurt McCullum wrote:
Guys, I did some testing on my T200 to figure out the whole serial
port wiring issue.
Test 1:
1. Write a test application to open the serial port on the PC with
DTR/DSR and CTS/RTS disabled
2. Go to TELCOM on the T200
3. STAT 98N1ENN
4. TERM
5. Press any key on the T200 and it freezes.
Test 1:
1. Write a test application to open the serial port on the PC with
CTS/RTS disabled but DTR/DSR enabled
2. Go to TELCOM on the T200
3. STAT 98N1ENN
4. TERM
5. Press any key on the T200 and it freezes.
Test 3:
1. Write a test application to open the serial port on the PC with
CTS/RTS enabled but DTR/DSR disabled
2. Go to TELCOM on the T200
3. STAT 98N1ENN
4. TERM
5. Press any key on the T200 and all data is sent to the PC and
sent back to the T200. Works perfectly.
I Then tested to see if TELCOM is actually using RST/CTS. For this I
wrote a small application to send a large file to the T200 with
Xon/Xoff turned off. I then put a bit of code in place to see if the
RTS/CTS flags were ever changed by the T200 to tell the PC to stop
sending. What I found was that the T200 never sent a flag to the PC
signaling to pause sending data due to the buffer being full. This
caused garbage on the screen.
So, what I can conclude from all of this is that the T200 serial port
hardware MUST have the RTS/CTS active or it will freeze the hardware.
But the TELCOM application does not use those signals to halt data
transfer when the buffer is full. Instead it relies on Xon/Xoff. Hope
that clears things up a bit on the mystery of the T200 serial port.
Kurt
