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This is the MPI Clone page.
A long time ago in a place far away . . . when I used to work at Tektronix,
and wanted an MPI, there stood up a clone that had 8 slots. Not only was
it done, it was announced as saleable. Like all important things, it fell
apart when my job there evaporated. I had even gone so far as to get a
company name, Only On Saturday Night (OOSN).
It started out as a joke; company? oosn, hahahaha. Oh well, I thought it
was funny at the time. Has the IdeZilla type front end connectors, so that
a cable can be hooked up and brought out to it, or just plug in to the
game connector.
Contains a fully buffered address and data bus, and a jumper to setup for coco-3's. You could use it on any coco-2, but the addressing range is limited. The mechanical switch is missing. CoCo-3 reset switch defaults to slot=0. Writing to the MPI byte ($FF7F), gives the same action for things like OS9. Writing the high-bit of each nibble, disables each -SCS or -CTS selector individually, allowing you to keep the slot#'s and loose functionality of either select on the fly. Interrupt connections come from the -CART pin, in each slot, then go through a 8-position dip-switch, then to a 2-way jumper. The jumper selects -CART or pin 1 of the coco-3's game connector. This allows the interrupt to be feed through without any flying wires, just connect the coco-3 internal pin 1 to the coco-3 internal interrupt of your choice, or set the jumper to use the default -CART interrupt. Obviously only for coco-3's, or those that don't have any power on pins 1 and 2. The addresses available at any slot is: $FF10-$FF1F or $FF30-$FF3F, decoded by address, or $FF40-$FF7F, determined by either decoding or the -SCS signal. Rom addresses are standard at $C000 to $FFEF, determined by the -CTS signal alone. Locked out are: $FF00-$FF0F and $FF20-$FF2F, obviously, since they are the PIA's.
It requires an external power supply, YES! The coco cannot supply power to this board, so it would be good for repacks.
Anyone interested? (The clickable image is 1024 x 324)
| The
byte at $FF7F:
76543210
If either enable bit is set to a 1, then that nibble is disabled, just that nibble. The byte at $FF7F is is write and read. Set bit 3: A=PEEK(&HFF7F): B=(A OR &H08): POKE &HFF7F,B Clear bit 3: A=PEEK(&HFF7F): B=(A AND &HF7): POKE &HFF7F,B The same for bit 7, except use: OR &H80; AND &H7F. |