[Coco] Multipak redesign/replacement

[RETRO Innovations]

On 2/24/2015 8:11 AM, Gene Heskett wrote:
>
>
> Working from memory, no.  Because I hacked the decoding in the packs such that
> my normally loaded packs, an fdc, a tc^3 and a dual port rs232 pack can all
> live together. And the wp-rs that is not now in the system since Boisy threw
> away my special drivers very early in his sysram wasting cutting up of
> drivers to make them one function drivers.  But he was running the show and
> my messages to him went into a black hole at the time.  The oem version of
> the wp-rs used 2 address in one 4 byte wide reservation and 2 addresses in
> the next one up, so that decoding and the driver got fixed in my own setup.
>
> So if the contents of the mpi are relatively fixed, any addressing clashes can
> be fixed in the pack itself.  But this of course works only for me and other
> hardware savvy folks, and is a dismal failure for someone who doesn't even
> know which end of a soldering iron gets hot, let alone follow the logic of a
> 74LS138. :(
>
> The ideal situation, but a non-starter, would be to put the address of the
> pack in ALL descriptors and decode on the mpi board to select which slot
> based entirely on the 4 byte wide i/o address in the descriptor.  That of
> course is a non-starter because the /CS logic in the packs would have to be
> bypassed and thats still a non-starter for the hardware compromised user who
> can't fix it on his own kitchen table.  All of the current fdc's waste a $10
> byte wide i/o space that with the full decoding could be limited to $08
> bytes, freeing 1 more address slot of 4 bytes,  And just that one additional
> space would go a hell of a long ways toward solving the I/O space problems
> the coco3's gime throws in our laps like a cup of McDonalds coffee.  Of
> coarse this doesn't fly if there is a real time clock. Mine had 2 but its
> been removed from the SC-II 4n1 for a while now. Running  a lot better on the
> tc^3 clock.
Well, I'd sure like to get more information.  I have some ideas, but 
need to understand the issue before suggesting one.

Jim