[Color Computer] Still more CoCo USB Was:[Coco] Re: Coco Digest, Vol 22, Issue 145

[James Diffendaffer]

> It's obvious to most here that the only real use for a
> USB port will be through OS-9 LII or Nitros9 (referred to 
> interchangeably as OS9 from now on).

Why not CoCo DOS?  Any program that outputs data through the standard
ROM calls could work.  Even programs that can't be patched for modern
printer drivers.  A virtual printer could translate between Epson or
Tandy and a USB printer like an HP Inkjet.  It would result in big
dots made of lots of little dots or require image enhancment but it
could work.  That could be done without a ROM.  

DOS calls could be intercepted as well but that eould be more complex
and would be best done in ROM.


> So one printer driver should work for nearly any USB printer -- just
> redirect output in OS9 to the USB port.

I'm not sure if printers are one of the devices that use a universal
driver.  Every USB printer I've used required a driver.

> multiple USB ports (say four) you won't need a disk controller.

Let's not say four and say buy a powered USB hub to protect your
nearly 20 year old power supply if you are going to be using many devices.


> One cartridge in the side, four cables running to a 1.44 floppy, a
> hard drive, a printer, and a thumb drive -- all easily available at
> the local PC store.

That I agree with.
My old CoCo drive isn't always happy and I'd like to use my USB drives
instead.  That's kinda why I got interested in doing this in the first
place.

> Make a boot ROM socket in that board too, just to be safe.

I'll think about it.  I think I still have some flash chips laying
around here but they are surface mount... which conflicts with the
user project idea.  I'm also not sure I have datasheets on them
anymore so I'm not even sure what the programming sequence is.

Just remember that I haven't built and tested this yet.
The design you see posted here was done in my head while I was writing
up the posts and when I could check pinouts and docs.  For some reason
I got started... so I kept going when I could till it was done.  I
posted the design as I thought it up.  It *is* based on what I had
started doing before but I didn't figure out the actual logic till I
started posting.  I still need to do a board layout.

None of the logic in this design is complicated.  One chip tests all
the high address lines, one all the low address lines and the other
chip is used to invert signals.  The circuit doesn't even require all
the available gates on the chips.

Still, I'd like to double check the logic levels of the CoCo buss and
Cypress chip before I build it.  The Cypress doc had pretty small
print on the diagram, the CoCo buss info came from a web page and so
did the timing diagram.  One misprint would cause it to do nothing,
respond at the wrong address or lose data at just the wrong time.






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