[Coco] 8 slot multi pak

[Mathieu Chouinard]

why just stop a 16 ;)

On Tue, Jan 17, 2017 at 3:19 PM, Brian Blake <random.rodder at gmail.com> wrote:
> Ed... I triple-dog dare you to make one...
>
> On Jan 17, 2017 2:46 PM, "Zippster" <zippster278 at gmail.com> wrote:
>
>> There’s an issue with going beyond 4 slots on an MPI, software support.
>>
>> The arbitration scheme using *CTS and *SCS traditionally only supports
>> for slots, so old software that uses these signals for selecting carts
>> would mean
>> you’d only be able to use the first four slots and stay compatible.
>>
>> Also, the *CART interrupt goes to the slot receiving *CTS, so autostart
>> carts
>> would be limited to the first four slots as well unless the arbitration
>> scheme is
>> extended.
>>
>> Now some things don’t use those signals, like the DACs on the Orch90, and
>> items
>> like that could go into extended slots without changing old software.
>>
>> A thought that occurs to me is that with the unused bits in the MPI
>> register at $FF7F,
>> the use of the *CTS/*SCS scheme can be easily extended to as many as 16
>> slots.
>> In fact, it looks like the bit locations might have been chosen with this
>> in mind.
>>
>> New software could easily support this, and perhaps old software can be
>> patched,
>> though at some point additional bus buffering may be needed.
>>
>> Thinking about it more, maybe this isn’t much of an issue.  You’d just
>> have to choose
>> what slots you use which carts in carefully depending on the software
>> you’re using.
>>
>> Someone please tell me not to make a 16 slot monstrosity just to make use
>> of those
>> register bits….   lol…  :)
>>
>> - Ed
>>
>>
>>
>> > On Jan 17, 2017, at 12:47 PM, Michael Brant <brant.michael.l at gmail.com>
>> wrote:
>> >
>> > Jim, it was my understanding is that you were building the mpi with the
>> > capability for 8 slots via 2 banks of 4.
>> >
>> > On Jan 17, 2017 1:39 PM, "RETRO Innovations" <go4retro at go4retro.com>
>> wrote:
>> >
>> >> On 1/16/2017 10:40 PM, Brian Goers wrote:
>> >>
>> >>> What is the status of the 8 slot Multi pak.
>> >>> How is the testing going?
>> >>>
>> >>>
>> >> I am finishing the final PCB design to the 4 port unit (with some relays
>> >> for power), but I am not aware of any 8 port testing.
>> >>
>> >>
>> >> Jim
>> >>
>> >>
>>
>>
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>>
>
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