[Coco] atari USB device

[jdaggett at gate.net]

David

When you get two or more peripheral devices on the bus you 
almost are destined to use handskaing and TDM techniques. The 
USB protocol has provision for handling low bandwidth devices and 
high bandwidth devices. When you get several large bandwidth 
devices on the bus at slow speed then the "effective" data transfer 
rate is far slower than that published. The problem with the Coco is 
that there is a point where a fixed number of low bandwidth devices 
will bog down the Coco due to the main processor constantly polling 
the peripherals querrying them if they have something to send.

I personally think that around three or four peripheral device will be 
the limit. After that some external processor will be needed and a 
large ram buffer,  8K comes to a nice usable figure. 


james
 

On 18 Nov 2004 at 1:25, David Hazelton wrote:

Date sent:      	Thu, 18 Nov 2004 01:25:30 -0500
From:           	David Hazelton <davehazelton at access-4-
free.com>
To:             	jhoger at pobox.com,
	CoCoList for Color Computer Enthusiasts 
<coco at maltedmedia.com>
Subject:        	Re: [Coco] atari USB device
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> John~
> Keyboards and Mice are slow devices.  Mark Marlett already has Compact
> Flash working and I believe that that is VFAT also.  I believe that it
> works under OS9/Nitro not DECB.  I do not believe speed will be a
> problem unless you are trying to write to a USB CD burner.  If one can
> get 127 devices per bus, one has to think handshaking of sometype is
> going on.
> 
> ~David Hazelton