Ok, here's a quick photo progression of the Intellicart, at least of the stages I have left. Click on any of the photos to see a larger version.
The first task was to build a cart reader to test how the Intellivision carts responded to various commands. Here's a quick photo of my
cart reader. Not directly related to the Intellicart, but since it contains the PIC that I originally planned on using in the Intellicart it's somewhat
related.
This is actually the last prototype. Most of the work was done on a breadboard with an old Poker cart used to plug into the Intellivision
with it's ROM removed and wires soldered to the former ROM's pads to connect the breadboard to the Intellivision. That went away when
I started working with the Intellivoice as I kept getting the strange error of no voice except "Mattel Electronics presents." First I wire wrapped the
breadboard circuit to create more sound connections, but still used the Poker cart to connect to the Intellivision. No effect. Joe suggested it was
bus loading due to the long leads, so I wrapped it onto the Vector C64 protoboard - still no effect. I THEN noticed that Mattel changed the pinouts in
Intellivoice carts. They grabbed two pins that were supposed to be ground and left them open. Those two pins were then connected to two control pins
inside the Intellivoice, so any non-intellivoice cart couldn't activate the Intellivoice because they grounded these control pins. The Intellivision is just
one annoying little trick or hack after another. Anyways, I opened up those two pins and everything worked fine. A lot of time and effort was wasted on
this problem. Numerous routes were explored etc. etc. In the long run it made for some improvements in the Intellicart algorithms, but mostly it was
just a large annoyance. I really wish I had inspected the carts earlier, but c'est la vie.
The other obvious part of the prototype is the microcontroller connected by all of those little wires. Let me give some advice on that right now: If you ever consider soldering individual wirewrap wires to a fine pitch smd - DON'T DO IT. That was a complete pain. I had my friend with far more stable hands help me accomplish that, but it was a long frustrating process and in the end almost made the part unusable. Why did I do it you ask? Well because the silly little part is in a 52 pin PQFP package, and since that's a very uncommon package sockets cost around $70.00. I later found one for $30.00, but still, $30.00 for a socket? Anyways, that's why the Intellicart now resides on a PCB.
This is the hopefully final version of the Intellicart, outside of its shell. The heart of the card is under the heatsink. The two 8-bit RAM chips used in the
prototypes have been replaced with a cheaper 16-bit RAM. I decided to take advantage of the new range of parts made available by printing a PCB.
(Parts that were only available as SMD.)