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Old Toy Modding?
Sqwubbsy writes "Stumbling through Google, looking for info on the Big Trak by Milton Bradley, I came across an article about one that was retrofitted with an OOPic controller. I was wondering if anyone else had a good story about a retrofitted toy that they beefed up?"
article text:
Retrofitting a Big Trak with an OOPic
Back in late 1979, Milton Bradley created a programmable 6 wheeled vehicle called the Big Trak. It was capable of performing 8 different functions and was considered programmable because it could store and play back a sequence of up to 16 of those functions. After reading the article in Ciarcia's Circuit Cellar Volume III, which was about creating a remote control for the Big Trak, my friend Louie ask for, and received one of these for Christmas of '82. We quickly exhausted all the creativeness we could muster out of Forward, Reverse, Left, Right, Fire, Repeat, Delay, & Dump trailer and decided that it was time that we take it apart and do something else with it.
Armed with an assortment of tools, we carefully poked, prodded and pried until the Big Trak was dissected. What we found inside was:
* 1 circuit board populated with 2 integrated circuits, 4 transistors and several other miscellaneous components.
* 1 24-key keypad
* 1 light bulb
* 1 speaker
* 1 dual dc-motor gear box with an optical encoder
* 1 9-Volt battery clip
* 1 4-cell D-sized battery box
Our focus quickly turned to the larger of the two ICs found on the circuit board. The IC was labeled TMS1000NLL and being the larger of the two ICs, it would be the microcontroller. If we were going to be able to program the Big Trak to something other than its original functions, the TMS1000 would have to be reprogrammed.
The TMS1000 Microcontroller was a Texas Instruments device. All the information that we had on this IC came from the Ciarcia's Circuit Cellar article which was quite clear in the fact that this IC could not be reprogrammed. What we needed was a small, lightweight computer that could be quickly reprogrammed, had at least 19 I/O lines and could be powered by batteries
At the time that we were doing this, we had two computers. A commodore-64 and an Atari 800. After some deliberation on whether or not the Big Trak could hold the weight of one of those computers plus some extra batteries mounted to the top of it, we decided that the Big Trak would just have to stay in its original condition. That is... until 18 years later.
The OOPic microcontroller is lightweight, fits nicely on the back of the Big Trak, has 31 I/O lines and requires no additional batteries other than the ones that the Big Trak used already. And even with the Big Trak using 19 I/O lines, there are still 12 I/O lines available for future expansion.
To mount the OOPic on the Big Trak, the panel on the back of the Big Trak was removed and 4 holes were drilled into the 4-cell D-sized battery case. The four screws were inserted from inside the battery case and nuts were then put on. This holds the screws in place and provides a stand-off for the OOPic. The OOPic was then placed on the screws, with the 40-pin connector towards the top, and 4 more nuts were added to secure it in place.
In the Big Trak's design, the TMS1000 was powered directly by the 9-Volt battery. This is very convenient because it brought 9-Volts directly to one of the pins on the TMS1000. As well as the power, all of the I/O used by the electronics of the Big Trak also connects to the pins of the TMS1000. Since every connection that the OOPic needs goes through the 28 pins of the TMS1000, all that will be needed to connect the OOPic to the Big Trak is a single 40-pin ribbon cable which will run from the OOPic to an adapter which will then plug into the same place that the TMS1000 is connected.
Before any connections can be made to the OOPic, the Big Trak's TMS1000 needs to be removed and replaced with a 28-pin socket. When the TMS1000's was desoldered, extra care was given to the traces on the circuit board. Since the circuit board only has traces on one side and the holes are not plated through, it is very easy to have some of the traces lift off of the circuit board. This can happen when too much heat from the soldering iron is applied for too