Reverse Engineering The Coleco Quiz Wiz
One of my biggest disappointment as a ten-year-old kid in 1979 was discovering that the Coleco Quiz Wiz handheld electronic toy gave identical answers for the first three cartridges. I could plug the module into any cartridge and answer 1,001 questions correctly since I memorized each question number and the corresponding answer letter.
If the answers were identical for the first three cartridges, the answers must be identical for the other 27 cartridges. I felt cheated by the non-randomized answers, which took the fun out of learning new trivia. Like many electronic toys that disappointed me, I took it apart to look inside, and tossed it into my junk box.
As a 51-year-old adult interested in the retro tech of my misbegotten youth, I wanted to reverse engineer the Quiz Wiz. Due to a lack of documentation for many handheld electronic toys from the late 1970s, the Quiz Wiz was a black box.
A black box is where the inputs and outputs are known, but how everything works inside is unknown. The inputs and the outputs often hint at what should be taking place inside.
Here are the steps for playing the Quiz Wiz.
- Turn on the Quiz Wiz.
- Press the CLEAR button.
- Type in the question number and the answer letter from the cartridge booklet.
- Press the ANSWER button.
- A correct answer will turn on the green light. An incorrect answer will turn on the red light and briefly sound a buzzer.
- Press the CLEAR button to start over again.
Here are the inputs, the outputs, and state changes.
- The inputs are a number (0–9, 1 to 4 digits long) and a letter (A-D).
- The output is either TRUE (green light) or FALSE (red light and buzzer).
- The CLEAR and ANSWER buttons trigger a state change within the circuit.
When I took the module apart as a ten-year-old, I recall seeing only one IC chip, some resistors and capacitors, and a speaker. The module ran on a 9V battery or an AC-DC power adapter. The IC chip was probably a 4000-series logic chip with a 5V to 15V operating range. The wiring to connect everything together for one logic chip to provide a binary answer (YES/NO) for 1,001 questions had to be quite clever.
I found a webpage to hack the Tiger Quiz Wiz electronic toy that came out in Great Britain during the 1990s. Whereas the Coleco had 30 cartridges, the Tiger had 60 cartridges. While the modules were functionally identical from the outside, the insides were quite different.
The Tiger module had a Field Programmable Gate Array (FPGA) chip to emulate the older logic chip and add extra features (i.e., an electronic voice for responses and a three-minute auto shutoff to preserve battery life), ran on a pair of 1.5V AA batteries, and didn’t have a jack for an AC-to-DC power adapter.
The Tiger module had a ten-pin connector for plugging into a cartridge. A simple circuit board on the cartridge connects the ten lines into different patterns to produce randomized answers. The ten lines may represent three groups and the other seven lines represented keys. If the math was correct, 50,400 combinations.
The Coleco module also had a cartridge connector but I don’t recall anything special about it. If the circuit board on the cartridge did randomized answers, the first three cartridges may have the same connector to provide the same answers. Subsequent cartridges may have different connectors.
If I were to pursue this project further, I would have to pick up a Coleco Quiz Wiz module with the Book 1 cartridge. Available for $20 USD to $30 USD (includes shipping) from eBay.
I’ve seen listings that offer the module with multiple cartridges for $50+ USD. A wide range of cartridges would determine if the answers were all the same or randomized.
With the Quiz Wiz in hand, I could open the module to see what logic chip was inside. Maybe I won’t find a garden-variety logic chip. I might find the 4-bit TMS1000 microcontroller that powered the Milton Bradley Big Trak, a programmable electronic vehicle toy from 1979 that also ended up in my junk box.