[Coco] I am looking for a few Code Snippets for the CoCo's.

[Mark D. Overholser]

On 17-Mar-17 14:48, Dave Philipsen wrote:
> I'm not familiar with the Apple Super Serial card but likely it used
> a UART as did the serial ports on the IBM PCs.  This is way better
> than the 'bit-banger' port on the CoCo because the UART takes care of
> the precise bit timing, buffering, error detection, framing, and
> assembling of the bitstream in the serial communications.  With the
> onboard serial port the 6809 must do all of that and it becomes quite
> a chore when you're working at bit rates above 9600.
>

The Apple SSC uses the 6551 ACIA, the same chip used in the Radio-Shack 
RS-232 Cartridge for the CoCo...   ( Strangely Enough, the Original 
Apple Serial Cards, there were Two, one for Printers and One for Modems, 
use the 6850 ACIA, which is a Motorola Chip, where as the 6551 is a MOS 
Technologies chip )


> Just as a SAM/GIME chip handles all of the video timings necessary
> for the CoCo that a 6809 could never do on its own, so too, a UART
> can handle a chore which becomes too tedious for the 6809 at anything
> more than the slower bitrates.
>

I agree...

> With dedicated UART/USART hardware you can free up a whole bunch of
> CPU time that could be well spent elsewhere.  I have a custom
> 6809-based FPGA design with a 250kbps USART, and three 115.2kbps
> UARTs and it can handle simultaneous communications over all four of
> them with ease even when the CPU core is slowed down to 1 MHz.
>

It is Amazing, what a small amount of Dedicated Hardware can do for 
efficiency....


> Dave
>

I am interested in Code for both the Built-In Serial Port and the RS-232 
Cartridge..   Since I am connecting this to a Lantronix UDS-10, the 
Hardware Specs say that the UDS-10 has 128 Kbytes of RAM..  So I would 
guess there is a bit of RAM used for Buffers.   The UDS-10 also supports 
XON/XOFF Flow Control, I should be able to have the UDS-10 Hold quite a 
bit ( relatively speaking ) of data, and then Batch Process it..

I am estimating that I will be looking at a Max of 1-2 Kbytes of Data 
per Transaction, so I should be just fine....

MarkO