[Color Computer] [Coco] Re: CoCo USB

James Diffendaffer jdiffendaffer at yahoo.com
Sun Jul 31 14:08:59 EDT 2005


> Anyway, the main reason for a USB port is easy peripheral access. 

A CoCo Floppy drive and controller can easily sell for over $50 on ebay.

A USB 3.5" floppy can be purchased under $15 on sale, it holds more,
offers more reliable disks you can still buy locally and the
controller can be used with other devices.  Hard drives, serial ports,
parallel ports, flash drives, keyboards, network interfaces, remote
controls... you name it.  

One interface that provides access to all that is a pretty good
investment.  Add flash memory (pretty cheap) and an RS-DOS replacement
or other boot code and it's a pretty serious upgrade for the CoCo.
It will probably even fit in a game size ROM pack.

> Doesn't matter if data rates are the highest, it still allows easy 
> connection to a lot of peripherals. That means just modifying a 
> generic USB driver to access almost anything.

The sample drivers are written in C and the open source project
drivers are 6502.  On top of that neither are designed to work with
RS-DOS or OS-9 so there is some work involved just in writing drivers.
 Some vendors also require special drivers for their devices so you
couldn't just buy any device that has a standard driver.  You would
need to stick to the ones that are known to work.

> There would be some 
> problems with transfer rates -- I know my desktop machine (about time 
> for an upgrade!) only has a USB 1.1 port and I have to burn CDs at 2X 

For a computer with multi-megabyte files USB 1.1 is slow.  For a
computer who's disks held 150K it's not quite such an issue.

> No serious CoCo3 user runs under 512K, and most have 2MB or more.

I'm not sure I'd agree with that but you may be right.
Personally, my CoCo3 has 128K.

> do the USB interface chips have an external buffer? That might be a 
> consideration also. 

The Cypress USB chip actually handles part of the USB protocol
internally so the host doesn't need to and it has 256 bytes of
internal RAM.

http://www.cypress.com/portal/server.pt?space=CommunityPage&control=SetCommunity&CommunityID=209&PageID=259&fid=10&rpn=SL811HS

> --
> Frank Swygert





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