[Coco] DriveWire survey

[CoCoList for Color Computer Enthusiasts]

On 5/11/2014 1:19 AM, CoCoList for Color Computer Enthusiasts wrote:
>
>
> There were/are all those plus some sound devices, x10 controller, weird
> drawing pad thing called xpad, probably more.  If its important I'm sure
> there is a comprehensive list somewhere.
Well, I'd only be interested in the biggies.
>
> Something that severely limits us with DriveWire now is that the bitbanger
> serial port must be polled for input, and doing that at 115kbps requires
> 100% CPU with interrupts masked.  This has the consequence that all I/o has
> to be initiated by the coco, no way for the server to tell the coco when
> data is coming in.  The DW driver has to constantly poll the server to make
> bidirectional I/o work.  It tries to adapt in real time to be efficient but
> its just not a good situation. If there was a buffer/UART on your device
> and it could raise the interrupt line when ready, that would open the door
> to vastly improved performance.

Looks like the CD line can trigger an IRQ.  Is that what you were 
thinking  Buffer some bytes in a uC, trigger the Coco, and it asks for 
the data?

Or, are you suggesting a cartridge that will IRQ when there is data to 
receive?

On the second idea, Looks easy.  NMI is available on the exp port...  
There's also CART*, but that looks specific to something.

Having a bit of trouble finding cart schematics, so links are always 
appreciated.

This:

http://sparksandflames.com/files/Color%20Computer%20RS232%20Pak.pdf

looks like !CART is used as !IRQ, but not sure.

Not sure on this one:

http://www.coco3.com/community/2010/06/a-dual-uart-with-fifo-card-for-the-coco/

Was there an official UART cart and is the schematic available anywhere?

Jim