Altair 8800 Serial Output

[rprouse]

I'm trying to get the Altair 8800 running 4K Basic with output to the serial terminal, but I think I'm missing something.

I've done the following,

• Added headers to the I/O board so that JP2 of the DE-10 Nano (TX, RX, GND) pass through to the USB user port on the I/O board
• Constructed a USB cable to attach the TX, RX and GND lines to an FTDI board
• Checked the continuity of the wiring from the IO15, IO14 and GND to the FTDI board
• Connected to the COM port using TeraTerm (and other serial terminals) at 19200 baud 8N1 with no flow control
• Set the Altair ON switch in the UI
• Set the STOP switch
• Set Basic4k32 as the program to load
• Toggled RESET switch in the UI
• Set RUN switch

The panel lights look like the program is running correctly and I've stepped through the first few bytes of memory, it looks like it is loaded correctly, but in the serial terminal I only see two letters RE.

The readme says "Comumicates with serial port requires SENSE swithes to be set to 0xFD" but I think that is left over from a different FPGA board?

• Is there anything else I need to do to get serial working through the I/O board on the DE-10 Nano?
• Do I need different serial settings? I'm using 8N1 and no flow control.

[EeDee]

I was looking at doing the same myself a few days ago but considered the possibility that it may not work and there'd be no help forthcoming. It's a niche core. Not much interest in it
What it needs, I think, is UART added thus dispensing with the need for the present setup but don't think there is much chance of that though.
Having said all that I hope you get it sorted if you have not done so already

[pgimeno]

Maybe you can ssh to the MiSTer and use Minicom? That should at least let you try different settings faster. It should work without any extra hardware too.

For ssh, if you're on Windows, look for PuTTY; that's an SSH client. If not, it's most likely already installed.

[rprouse]

Maybe you can ssh to the MiSTer and use Minicom?

That is a good idea but it didn't seem to work for me. I didn't even get the RE letters I got before.

I tried /dev/ttyS1 and /dev/ttyS0. I checked and UART mode is set to 0 which is I think correct. I tried various combinations of settings and flow control, but nothing.

I referred to this, viewtopic.php?t=2724

Next step is to dig out my logic analyzer and connect it to the RX/TX lines to see if there is any data on the wires.

[EeDee]

I tried /dev/ttyS1 and /dev/ttyS0. I checked and UART mode is set to 0 which is I think correct. I tried various combinations of settings and flow control, but nothing.

I referred to this, viewtopic.php?t=2724

Next step is to dig out my logic analyzer and connect it to the RX/TX lines to see if there is any data on the wires.

Please let me know how you get on

[EeDee]

What it needs, I think, is UART added thus dispensing with the need for the present setup but don't think there is much chance of that though

That should be "vdu console" not "UART"

[rprouse]

Still no luck, but I think I've ruled out serial settings. I connected a logic analyzer to the TX/RX pins 15/14 and used a UART protocol decoder set to 19200 baud 8N1. I see three bytes on the wire, CR, R, E which is the same as I see in the terminal.

zqBLSKfx.png (45.02 KiB) Viewed 2293 times

To me, this means that the circuit from the DE-10 through the I/O board to the FTDI are correct and my terminal settings are correct. If that is the case, then it is a software/config issue,

• I am using the core wrong,
• There is a bug in the core, or
• There is additional MiSTer FPGA setup I need to do to get UART working

Ideas are welcome

[EeDee]

I tried /dev/ttyS1 and /dev/ttyS0. I checked and UART mode is set to 0 which is I think correct. I tried various combinations of settings and flow control, but nothing.

I referred to this, viewtopic.php?t=2724

Next step is to dig out my logic analyzer and connect it to the RX/TX lines to see if there is any data on the wires.

Please let me know how you get on

Thanks for the update although no suggestions I'm afraid. Will give it some thought though

[EeDee]

quote]To me, this means that the circuit from the DE-10 through the I/O board to the FTDI are correct and my terminal settings are correct. If that is the case, then it is a software/config issue,
I am using the core wrong,
There is a bug in the core, or
There is additional MiSTer FPGA setup I need to do to get UART working
[/quote]
Here's a bit of a rabbit hole. If you go down it though, unless you've done so already, there may be a clue pointing to why core is not working properly.
viewtopic.php?f=13&t=1949
Note @bbond007 's Post