[Coco] 6 Chip ^809 Computer -> Kipper SBC

[RETRO Innovations]

On 3/14/2015 2:09 AM, Kip Koon wrote:
> Hi Jim,
> I was not aware of that.  It never made sense to me that Tandy would put slow baud rate chips into the RS-232 paks.  Why do I keep hearing from time to time, that 19,200 is the best baud rate that can be gotten from the paks then?  Is it how the chip is set up or is the implementation incorrect for the higher speeds like 115200 and 230400?
Well, the MAX232-like IC in the Pak might not work at that speed, but 
the 6551 can indeed go at that speed.

The trick is that the 6551 has a special "baud rate" called "CLK/16"  
When in that mode, the bps rate is 1,843200/16 = 115200. It was 
popularized in the CBM arena by the Swiftlink-232 cart long ago, which 
doubled the clock speed going in and used a 6551A to get 230400bps using 
this mode:

https://www.commodoreserver.com/BlogEntryView.asp?EID=FA5AE758474345A9A0A7208C7F408538

I am sure other things did the same.

Jim