[Coco] Multipak redesign/replacement

[Gene Heskett]

On Tuesday 24 February 2015 21:03:57 RETRO Innovations wrote:
> 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

Ask away Jim. You can go to PM'ing me, but I would rather that anyone on the 
list who can understand what I'm saying in those areas where I do have 
decades long experience with, a chance to learn something for their own 
edification.  Hopefully I just did that with my Transmission lines 101 
message of ten minutes ago.

Cheers, Gene Heskett
-- 
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