Coco 2 Serial Output

[ryushi5]

I'm new to 8-bit machines, and this is my first Coco 2. So far, everything seems to work on the machine as it appears to be in very good condition. The only thing I have found so far is that the large 4700uF cap seems to have leaked a little, and I have a replacement coming for it.

 

Here is what I am having trouble with: I would like to output simple serial communication using the RS-232C port. Nothing complicated, just a few characters.

 

The only way that I have found to do this so far is to print as if to a printer with the command below:

    PRINT #-2, CHR$(49)

 

Whenever I attempt to print like this, the machine freezes and will not respond to any inputs unless I reset the machine.

 

I have tested the RS-232C output by poking 65312 as suggested in the repair manual. This works, and I get a little less than 5V between GRD and pin 4 on the JK3 port.

 

Any thoughts on what I'm doing wrong?

[jhd]

 

It has been a REALLY long time since I used my Coco, but I wonder if it is waiting for an acknowledgement signal from the (non-existent) printer?

 

 

[ryushi5]

That's something I was thinking as well. But when I have my o-scope connected, I don't see any attempt for the machine to send a signal. Of course, maybe I'm just missing it.

[ryushi5]

Are there any alternative methods in BASIC to send serial data?

[jhd]

Sadly, no. 

 

Quote

DLOAD is the most obscure command in the Color Computer and absorbs a substantial amount of space in the ROM. DLOAD is so poorly understood because Tandy has never made the necessary companion routine, DSEND. DLOAD will DOWNLOAD a file over the RS 232 line from another system, however there is no companion routine, which will transmit a file over the RS 232 line to another Color Computer. Once a DSEND routine is built and made available to the masses, DLOAD will be much better understood.

Extended Basic Unravelled II p. 5

 

This commented ROM source code may answer the questions about the serial port. 

 

 

 

[linville]

PRINT #-2 expects a printer at the other end of the line, which it expects to drive a BUSY line (low for busy, high otherwise). To capture the input over a "normal" serial port, you'll need to pull line 2 on the 4-port serial port high, as indicated below...

 

There is nothing in Color BASIC or Extended Color BASIC that accepts serial input, other than the DLOAD command. DLOAD servers exist from antiquity, but they are hard to locate these days -- may the Google be with you... (e.g. https://willus.com/trs80/?-a+5+-p+124632+-f+23)

[ryushi5]

That's great information. Thanks very much! I'll do some experimenting and see where I get.

[Mr SQL]

If you launch The Best BBS and then hit break you will return to BASIC at 300 baud with IO mixed in through the bit-banger. 

 

 

 

 

[MarkO]

If you want to work with 6809 Assembler, here is Bill Yakowenk's Page with some Bit Banger Serial Routines...
http://www.cs.unc.edu/~yakowenk/coco.html#local

 

MarkO

[Mr SQL]

On 11/7/2019 at 3:01 PM, ryushi5 said:

Are there any alternative methods in BASIC to send serial data?

 

On 11/7/2019 at 3:42 PM, linville said:

PRINT #-2 expects a printer at the other end of the line, which it expects to drive a BUSY line (low for busy, high otherwise). To capture the input over a "normal" serial port, you'll need to pull line 2 on the 4-port serial port high, as indicated below...

 

There is nothing in Color BASIC or Extended Color BASIC that accepts serial input, other than the DLOAD command. DLOAD servers exist from antiquity, but they are hard to locate these days -- may the Google be with you... (e.g. https://willus.com/trs80/?-a+5+-p+124632+-f+23)

 

On 11/8/2019 at 2:11 AM, Mr SQL said:

If you launch The Best BBS and then hit break you will return to BASIC at 300 baud with IO mixed in through the bit-banger. 

Ryushi I found the setup disc that will enable transparent bi-directional communication for BASIC through the bit-banger port:

BBSMLNG1.DSK

Create a real disc image or drop it on your SD drive, anyone who wants to explore it can also use the online CoCo emu Mocha: 

https://www.haplessgenius.com/mocha/

 

The instructions are timed at 300 baud which is pretty cool to watch:

RUN "USER" 

 

The instructions tell you how to run SETUP, I was amazed how similar it is to the way we configure server software today... nothing really changes

There's also this CoCo Demo on the disc but you'lll need a CoCo3 or the CoCo3 emulator to run it:

RUN "BBS AD"

 

BBS Server images from the 80's and 90's 

 

The BBS image discs of live installs from the 80's and 90's and even current installs Today are disconnected forum servers with their information frozen in time, waiting to be discovered one day by digital archeologists.

 

This thread shows an example logging in to read user messages from 1994 using the default SYSOP password.

Sysadmins never change their passwords simply because they cannot forget them.

    

[MrDave]

I was able to get serial data out on my coco2 by jumping pin 2 of the serial port to the joystick +5v then i took the rs232 out ( pin 4 )to an inverter nand gate i was able to get 600 baud .. 1 low stop bit 8 data bits lsb first and 2 stop bits using print #2, chr$(data);

Each bit was 1.65 ms 

I am going to be playing with this more to see what i can do with this.. maybe drive a small lcd screen,,