[Coco] WiFi modem.

[Gene Heskett]

On Saturday 20 January 2018 12:44:50 RETRO Innovations wrote:

> On 1/20/2018 4:09 AM, Gene Heskett wrote:
> > On Saturday 20 January 2018 04:12:37 David Ladd wrote:
> >> On Sat, Jan 20, 2018 at 2:12 AM, Gene Heskett
> >> <gheskett at shentel.net>
> >
> > wrote:
> >>> On Saturday 20 January 2018 01:30:46 RETRO Innovations wrote:
> >>>
> >>>
> >>> ​<cut>
> >>>
> >>> So it boils down that I am not in a position to advise, just warn
> >>> that all facets need to be checked. With the speed limits of the
> >>> coco in handling an error correction protocol such as rzsz, flow
> >>> controls are a must when the baud rate goes above 240. Even less
> >>> if its multitasking heavily.
> >>
> >> ​Gene, in this case Jim could more than likely easily make a
> >> version of his board using two 6551's for compatibility and set one
> >> 6551 to the standard Deluxe RS232 address space and then set the
> >> second 6551 to the Modem Pak's address space.  I myself would even
> >> love one of these. :D (wink wink)
> >
> > I have fought with the limited i/o space in the coco's because of
> > tandy's decision to use a $20 wide space for a pia that needed 4
> > bytes, not once, but twice! Properly decoded, that wastes 7 usable 4
> > byte wide i/o spaces per each pia.
> >
> > Thats room for 14 more i/o gismo's without any address clashes with
> > existing stuff we all own.
> >
> > I have even gently begged the layout expert folks like Jim and Ed,
> > even Roger, to make us a kit to fix that. But apparently with the
> > number of different boards over the years, its not practical
>
> The problem is not practicality, but of combination.  Removing the
> "mirrors" (repeated address ranges are termed "mirrors") only makes
> financial sense to implement when you have something to put in those
> mirrors.  No one wants to buy a "de-mirror" device that offers no new
> functionality.
>
But, it enables cards in the cartridge port/mpi that use full address 
decoding to work at these newly available addresses, this is the 
precursor dependency. Imagine what we could do with even one pia fully 
decoded, that 7 more addresses that are then usable by anything you drop 
into the mpi. Those unused cs's don't need exported, can't be, not 
enough pins in the cart interface, but thats 7 or 14 (I think the same 
drop-in board in the coco could work for either pia by using that chips 
cs as an input to the board) new addresses usable for each drop-in 
postage stamp.

> So, if we can decide what needs to sit in those mirrored locations,
> the CPLD or FPGA can happily remove the mirrors and place the new
> functionality in that space.

Dip switch program the new devices address, put its address in the 
descriptor. Then anyone with any familiarity with decent soldering tools 
can do it. And its not then a matter of deciding what goes where in any 
arena but the users own workbench.

> Jim
>
> --
> RETRO Innovations, Contemporary Gear for Classic Systems
> www.go4retro.com
> store.go4retro.com


Cheers, Gene Heskett
The above content, added by Maurice E. Heskett, is Copyright 2018 by 
Maurice E. Heskett.
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