RomWBW and serial baud rates

[Martin Giese]

Hi again :-)

Emboldened by my success with the RTC driver, I wonder how much effort it would be to put the serial speed in my setup under the control of RomWBW.

I use a SIO/2 but I don’t have a CTC.  The clocks for the two serial ports are generated from the system clock by a CPLD.  The two speeds are controlled by writing a byte to port 0x84, one nibble for each of the SIO ports. Each nibble is an "encoded baud rate" with an encoding similar to the 5 bit one used in RomWBW.  I figured I won’t need anything slower than 300 baud, so 4 bits are enough.

What would I have to do to be able to control serial characteristics using MODE.COM?

No really pressing issue, I have my own utility to set the two speeds conveniently.  Just curious.

Martin

[Peter Onion]

On Sun, 2025-06-08 at 12:52 -0700, Martin Giese wrote:
> Hi again :-)

>
> What would I have to do to be able to control serial characteristics using MODE.COM?

There is mention of setting baud rates in RomWBW System Guide, 
Sections 10.3 Character Input/Output (CIO)
and
10.3.5 Function 0x04 - Character I/O Initialization (CIOINIT)

HTH,

PeterO

[Wayne Warthen]

To expand on Peter's reply, you just need to handle the CIOINIT function within the sio.asm driver.  When called, the requested line characteristics are in DE.  You will need to translate to your CPLD coding.  The sio.asm driver currently has a lot of code to program a CTC.  You will need to bypass or remove that and use yours instead.  The MODE command should just work without any changes.

Thanks, Wayne