[Coco] MPI replacements?

[Gene Heskett]

On Thursday 08 July 2010, Frank Swygert wrote:
>I remembered at least one MPI replacement -- the Slot Pak II (and later
> III?). Found some more info on it at
> http://entropy.tmok.com/~tumble/cfaqs/COCO.FAQ. It seems that "our" very
> own Chris Hawks designed and sold it, maybe he could be talked into
> making another run? Only three slots though.
>
>A company called "Orion" also made a three slot MPI replacement. It had
> the cartridge connectors on a cable though. That would make it the best
> choice for repackaging a system where the carts weren't going to be moved
> much -- they would have to be secured somehow inside the repack case.

I have one of those, POS.  You are dependent on the single ground pin in the 
cable and because of data clashes because two different sources are trying 
to drive the data bus at the same time for about 10ns on the read/write 
changeover, I found the crash rate was in crashes per second.  Adding the 
extra grounding of the ear clips fixes 99.9% of that.  It would probably be 
ok if the carts pcb's were all firmly mounted and their grounds well 
connected though.

>This is the ONLY mention of these devices I could find using Google
> (searched for "coco slot pak" and "coco xport"). I'd check the Rainbow
> archives for pics, I do recall seeing at least the Slot Pak in ads. I'd
> check about a year after the demise of the MPI... 1989 and later?
>
>----------------------
>
>  Slotpak (as excerpted from Marty Goodman's review by permission)
>
>There are now two new entries into the field of Multipak replacements:
>Howard Medical's "Slot Pak II" (designed by Chris Hawk of Hawksoft) and
>the Xport from Orion.  Both offer three buffered slots.
>
>     .....
>External Appearance:  The Slot Pak II (SPII) is packaged in what appears
>to be an old, full size, disk controller plastic  case.  There are three
>40 pin edge card sockets sticking up on top  of the case thru holes in
>the case.  There is a jack for connection to a 12 volt wall transformer
>(supplied).  Glued to the bottom of the pack is a U-shaped piece of
> plastic that supports the SPII, so that the weight of devices plugged in
> to it does not produce leverage that would deform the CoCo's 40 pin
> expansion socket. This is a nice touch, for the SPII plugs directly in to
> the expansion socket, and cards plug in to the three slots on the top
> surface of the SPII.  There are no mechanical guides for ROM packs or
> cards... the edge card connectors are their sole support...
>
>...The device uses ten small scale (74 series) logic chips internally --
>three for buffering address and data lines and the rest for slot
> selection...
>
>
>    XPort by Orion  Technologies excerpted from a New Product Release.
>
>The XPort  is  Orion's  answer to the latest of Tandy's casualties, the
> Multipak Interface. While the XPort  is  not  a true duplication of the
> Multipak, it contains all of the necessary features that the common Color
> Computer user needs - Multiple slots, a fully buffered  bus, slot
> switching, and a  power  supply external  to  the  CoCo  for the added
> cartridges which includes +5 and +/-12 volts.
>
>... We offer not just two, but three slots with which to  work.  These 
> slots are  configured  to  allow  hardware  switching of the cartridge
> ROM in two of the slots, with the third slot being utilized for
> cartridges that have no internal software  - such as the Telepak II, 
> Tandy's  Speech and Sound cartridge, a MIDI cartridge, etc.

This 'cable' I have, has no logic in it at all.

>We gave the XPort something that  was  sadly lacking with the MPI, and
> that was MOBILITY.  Since the XPort terminates  as  a  cable,  the 
> working end of  the cable  with the peripherals installed can be moved
> out of sight by merely placing them  where you like within 15 inches of
> your computer's cartridge  port.  The buffered bus allows  a  stronger
> signal, allowing the longer cable length than a standard "Y" cable.
>
>The XPort's  internal  circuitry  will  be  powered  by  your Coco,
> drawing less than  a  standard  disk   controller,   and  all  external
> peripherals will be powered by an external wall transformer (supplied)
> and voltage regulation circuitry that  is  external to the Coco's own 
> power supply. The +/-12 volt (30 mA  max. each) is provided by a DC-DC
> convertor in the  XPort, and supplies enough power for  the Burke and
> Burke XT interface, an older 12 volt contoller, or other devices (such as
> Disto's RS-232 cartridge).
>
>The XPort has been designed to allow  all I/O to occur from address&HC000
> (49152), the external ROM address, and up. ...

So any of these would be a better designed solution than what I have in the 
coco's spares cabinet.

-- 
Cheers, Gene
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