[Coco] Educate me about Y-Cables

[Zippster]

Cool, sounds like a pretty good plan.

There’s always the 100 pin TQFP package if you need more pins on the 9572xl.

- Ed

> On Feb 20, 2015, at 11:06 PM, RETRO Innovations <go4retro at go4retro.com> wrote:
> 
> On 2/20/2015 8:09 PM, Zippster wrote:
>> I guess I was really thinking something very simple mainly so I could use 1 additional
>> slot.  Like an SDC along with a real floppy, or sound cart, or RS-232, etc.
>> 
>> I think someone else is working on a new MPI (Retro Innovations?) so I didn’t really
>> want to get into that at the moment.  Buffering and some DC power from a wall-wart is easy
>> enough though.  I'll see what I can come up with.
> Well, don't quit on my account.  But, slow though I may be, here is what I have done:
> 
> * I made an order for some 40 pin .100" edge connectors
> * Ordered a batch of xc9572xl CPLDs, which I can program
> * Started working on the design, which is mainly in the CPLD. The CPLD
>   will hold the IO register and handle the logic on the MPI in the
>   PAL, the LS374, LS367, LS139, LS368, LS74, LS30, and LS153
>     o buffer all the same lines as the original MPI, but I am planning
>       to use 74abt541s instead of 74ls367s for the address lines and
>       such, but using a 245 for the data lines, as before.
>     o put the following Coco lines into the cpld (32 lines)
>         + 8 data lines
>         + 16 address lines
>         + CTS
>         + SCS
>         + Q
>         + E
>         + SLENB
>         + CART
>         + RESET
>         + R/W
>     o and from the cart slots (12)
>         + 4 cart lines
>         + 4 SCS lines
>         + 4 CTS lines
>     o and to/from switches and LEDS (6)
>         + 2 lines for initial slot selection
>         + 4 lines for LEDs
>     o That uses 50 of 52 lines on the CPLD (VQ64 footprint), and I
>       think I am still missing a few signals I need.  I can forego the
>       upper 8 address lines (like the real MPI), but would prefer not to.
> * Bought a small ATTINY AVR to do the switch to 2 slot select line
>   conversion, though might do something else.
> 
> I have an EAGLE footprint for the edge connector and the female version, but am always interested if there is one that includes the grounding fingers.
> 
> Since I am planning to be at CocoFEST, I am trying to get this done in time to bring.
> 
> JIm
> 
> 
> 
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