[Coco] SD Card reader/writer or USB

[Aaron Wolfe]

On Oct 9, 2014 12:49 AM, <nickma2 at optusnet.com.au> wrote:

>
> Drivewire is also a groundbreaking product although a shift from
> Serial to USB may be needed one day since serial is no longer found on
> computers.
>
> I wonder, with the required voltage conversions, is it possible to
> make the bitbanger serial port act like a USB port?
>
> May open the door for other USB devices as well such as USB drives and
> mice.

There are a few things that come to mind here.

As for changing DW to "use usb", in the practical sense it already does
since usb serial dongles are readily available and cheap.  Many newer
devices that have a usb port on them (most ham radios with a "usb"
connection for example) just have a usb serial adapter built inside them,
so the mechanism is still a current one.  Serial I/O is still a very
reasonable way to communicate even in our modern era.

So cheap adapters solve the problem of using something that doesn't have
built in serial but does have usb (many modern PCs, rasperry pi, etc) as a
server.  Another alternative is a Bluetooth serial adapter, which lets you
use things like most any android phone or tablet as the drivewire server.
Realistically I don't think there is a need to use something different for
a connection via the bitbanger since ultimately the bitbanger will always
be a serial device.

On the other hand, thinking beyond what drivewire does and on to allowing
the coco to communicate with USB devices itself is a good idea.  USB is
actually a fairly complex protocol and interfacing with it would mean tying
a controller to the coco that is probably more powerful in many ways than
the coco itself, but that's a bridge many of us have already crossed and
made peace with.  It would probably make more sense to use the coco bus
rather than the bitbanger for such an interface.

Going a step further, what if you could add not only USB, but also Ethernet
and an SD card reader at the same time? Stick a raspberry pi in a rompak,
figure out an interface to the bus (SPI?) and you've got a whole world of
modern I/o options.  But, you've also got an entire computer that's many
times more powerful than the coco acting as your I/O processor.   There are
precedents in computing,  for example the big iron mainframes and
supercomputers often have very powerful computers dedicated to I/o, and
even commodore 64 disk drives contained processors at least equal to the
one in the "computer" if I recall correctly.  But it does start to feel
weird pretty quickly.  No weirder than using a second pc just for DriveWire
I suppose, and a lot more functionality.

Anyway, that'll be $0.02