[Coco] Re: Why USB would be nice.

[John R. Hogerhuis]

On Fri, 2005-09-02 at 11:32 -0700, Kevin Diggs wrote:
> John R. Hogerhuis wrote:
> > On Thu, 2005-09-01 at 21:19 -0500, George Ramsower wrote:
> > 
> >> If I were to purchase the hypothetical USB card and the driver for OS-9, 
> >>would this do as I want or expect, such as.....
> >>
> Unless you are an idiot (or very, VERY patient), you can't expect a sub 
> 2MHz computer with a 64k address space to be able to do the same things 
> with a USB critter that a 3.0GHz machine with a 4G address space can.
> 

I'm neither an idiot nor patient. Should I be offended by your remark? I
choose not to be.

In fact, I'm a firmware engineer. I deal with underpowered machines as
my profession.

It's hard to know at this point what will be possible and what will not.
Storage I think is going to work just fine. It will be slower than on a
desktop machine, that's a fact. WIll it be slower than Coco hooked to
IDE? Probably.

Plus, one still has to develop a FAT32 file system implementation. But
if one wants to use flash as a sneakernet between machines, whether with
SuperIDE or coco-usb or whatever, it's a necessary evil.


That's one of the fun things about the coco... pushing it to do things
everyone would say "you can't do that!"

You certainly don't need a machine with 3GHZ and 4G of address space to
be a USB host. The project banks on the fact that The embedded USB
controller chip offloads a lot of work from the CPU.

> 	As I understand it, USB is kinda similar to SCSI, at least for 
> semantics (not an english major - probably not the word I was looking 
> for) (There is a SCSI host adapter driver and drivers to support various 
> device types (disk, cdrom, tape drive, scanner)). "The driver that came 
> with the card" (port driver) would be analogous to the host adapter 
> driver. You would also need drivers for each type (class?) of device you 
> want to torture your tre with.

Yes you would need drivers. I presume you would contruct a kernel with
drivers only for the hardware you use though.

I'm not sure what your definition of torture is, but it sounds like it
differs from mine in important ways.

> 
> 	Since USB is hot-pluggable, how would that be handled? Correct me if 
> I'm wrong, but OS9, while I think it can load drivers and descriptors 
> "on the fly", doesn't the text for each get a fresh page (i.e. can't 
> pack text on the tre)? Won't this fill up the system map quickly?
> 

As I understand it, with level II you can pack multiple modules into an
8K block.

Take a look at the drivers over at microusb.org . If you think of USB as
some nightmare stack of code, you may be pleasantly surprised to see
what the 6502 folks have done.


-- John.