[Coco] Reading data through the bitbanger port

Salvador Garcia salvadorgarciav at yahoo.com
Mon Mar 29 16:16:41 EDT 2021


 Tim and Dave, thank you for your feedback.
Yes, I was thinking asm language for this. However, I distinctly remember that someone had posted an asm routine to read from the serial port. I just can't remember who. I also posted this question on FB and Discord, hoping that someone might remember, or that the author might see it and chime in.
Personally, I don't have enough experience with asm code to outright write it without overcoming a steep learning curve. I will read the RS232 primer and keep looking for CoCo asm snippets that can do this. Again, much appreciated! Saga


    On Monday, March 29, 2021, 12:25:08 PM CDT, tim lindner <tlindner at macmess.org> wrote:  
 
 On Mon, Mar 29, 2021 at 10:04 AM Salvador Garcia via Coco
<coco at maltedmedia.com> wrote:
>
> Hi all, I am interested in knowing how the CoCo serial port works.

You have to use assembly language, because the signals change way too
fast to handle in BASIC.

But the short and sweet info dump is:

Read serial data by reading $FF22 bit zero.
Write serial data by writing to $FF20 bit one.

http://tlindner.macmess.org/wp-content/uploads/2006/09/cocopias-R3.pdf

Here is a nice article about the RS-232 protocol, both software and
hardware aspects.

http://wilsonminesco.com/RS-232/RS-232primer.html



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tim lindner

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