[Coco] Bit-Banger Serial as external console?

[Brendan Donahe]

Stephen,

I recently had this same problem.  I couldn't find good BASIC ROM calls to
do what I needed (potentially bi-directional w/o concerning myself with the
CD pin), so I derived some of it from Bill Yakowenko's site (look for COMM4
on http://www.cs.unc.edu/~yakowenk/coco.html) and rolled some of my own.  I
have some assembly language routines that work at 9600 baud.  I'll contact
you off-list with some of this info, and you can see if it will help you
achieve what you're trying for.

Brendan

On Mon, Mar 25, 2019 at 2:18 PM Stephen Pereira <
stephen.m.pereira.sr at gmail.com> wrote:

> Hello folks,
>
> I’ve been dormant for quite some time on this list and with my CoCo…
>
> I have a stock CoCo 3 with Zipster’s SDC, and that’s all right now.  As
> you may recall, a couple (few?) years ago, I modified the Talbot
> Microsystems Color Forth to work in RAM along with DECB.  I have that
> running on my SDC, and I’ve been searching around for a project to work
> on.  All my other vintage computer systems use my laptop computer as an
> external console.  This allows me to work on programs externally and send
> them in to the computer system, rather than tediously type them in on the
> vintage machine.  Not so with the CoCo.  Since the CoCo is an all-in-one
> system, I have no external console to send my programs in from, as with my
> other machines.
>
> I would love to add an external console to my CoCo.  I thought this might
> be a good project to get me back into Forth programming.  I looked around a
> bit, but I have not found any information on system calls that can be used
> to perform character input and output via the bit-banger serial port.  I
> saw in the “Unraveled” book for the CoCo Basic ROMs that the is a ROM call
> for doing output - quite logical, since this port was used for the printer
> output port.  But I have not found anything about doing input from that
> same port.
>
> Since Drivewire uses that port, I know that it can do both output and
> input.  Can anyone provide me any pointers to information on using the
> bit-banger serial port?  Any code examples would be appreciated.  My intent
> is to write up my code in Forth to add an external console.  I can start up
> normally, then invoke the code to switch to the external console.  I figure
> that I can use a control-z or something like that as a flag to switch back
> to the normal console after I’ve sent in my code.
>
> Thanks very much, in advance, for any thoughts, pointers, or advice that
> you may have to offer.
>
> smp
> - - -
> Stephen Pereira
> Bedford, NH  03110
> KB1SXE
>
>
>
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