RSGC ACES: Binary Challenge (New for 2019-2020)

For over a decade, Grade 10 ACES have undertaken friendly tournaments to promote mastery of the binary number system. Initially, Cisco Systems hosted a freely accessible page entitled the Cisco Binary Challenge. In 2014 Cisco required users to create a (free) account to access this recreational activity. Since we're not big fans of data tracking we've turned to the (anonymous?) online app version developed by Studio Code in recent years. However, since ACES pride themselves on being drivers of technology, not just users, developing their own tools and instruments comes quite naturally. A dream for these past 10 years has been to create our own class set of handheld programmable versions of the Binary Challenge. A number of partially successful student attempts have been undertaken as ISPs (see our development page) in past years. In early 2019, with our 3D printing facilities sufficiently mature, a summer collaboration with one of my talented design students (K. Fiset-Algarvio; ACES '19) produced cases for a class set 30 RSGC ACES Binary Challenge units, materializing in late August of 2019, just in time for the start of the 2019/2020 academic year. Click on the image to the right to see a detailed photo of this one-of-kind training device.

This device is a prime example of the three domains ACES pursue vigorously: hardware, software, and design. On the software side, these units offer five separate 8-bit binary challenges: Unsigned, HEX, Signed, ASCII, and Fixed Point (Q5.3) each of which is user-selectable. An external ISP header allows for 'in-place' updating of the firmware.

I am confident a training device like this is unique to RSGC and we are extremely fortunate to have this tool available, both as a practical instrument for exploring the binary number system from Grades 5-12, but also as a model of the unique secondary school engineering capabilities undertaken in the DES. Perhaps the single drawback is the expense of its creation. At just over $100 for parts alone, coupled with hours worth of 3D printing and manual assembly per unit, these devices are not easily replicated (otherwise, it would easily qualify as ACES' first Kickstarter initiative due to its unique appeal).

It is hard to express the degree of pride embodied in this achievement. In the truest sense, our Binary Challenge represents the enormous advances our ACES program has made over the past 16 years, due almost entirely to the talent and brilliance of Georgian ACES and Mr. Paul Elia, our DES Design Consultant.

If you ever find yourself in the area of the DES after school, drop in and try your hand. Caution: even practicing can be addictive :)


  1. The I/O power rocker switch is located on the back, closest to the 9V power receptacle. When activated, the green 3mm LED will light.
  2. The MODE rocker switch, next to the I/O switch, selects between the two games in the current firmware (primary and secondary). When the secondary game is active, the red 3mm LED is lit. Note: toggling between games immediately zeros your SCORE.
  3. The larger 0.56" blue 4-digit, 7-segment display is the VALUE you are required to emulate using the 8 rocker switches which add the respective binary power weighting to the VALUE.
  4. The smaller 0.39" green 4-digit, 7-segment display is your SCORE. 30 points are awarded if you achieve the presented VALUE in under 5s, 20 points are awarded if you achieve the VALUE in under 10s, and 10 points are awarded when you achieve the correct VALUE, regardless of how long it takes you.

Five Different Binary Challenges

A. Unsigned. This is the vanilla, 8-bit positive integer model spanning the closed interval [0,255] in which the binary power weightings are as etched onto the acrylic top and silk screened on the PCB. The binary point is assumed to be to the right of the rightmost switch and all eight switches influence the integer part of the VALUE.

B. Hexadecimal BCD. Each VALUE is to be interpreted as a pair of binary coded nibbles presented as hexadecimal digits 0..F. Users interpret each set of 4 switches as binary weightings of 8-4-2-1. For example a VALUE of A7 would be represented as 1-0-1-0 0-1-1-1.

C. Signed.In this challenge, the VALUE display is capable of presenting any of the 256 integer representations of signed 8-bit values under the 2's complement algorithm span the closed interval from [-128,127].

D. ASCII. The VALUE displayed is a 7-segment representation of an uppercase ASCII letter as depicted in the underlined area of the image below. Users are required to enter the value over the closed interval [65,90] that corresponds to the letter.

E. Unsigned Fixed Point: Q(5.3). Unless otherwise indicated in a computing context, the binary point is assumed to take up a position to the right of the rightmost bit presented. This is the case with the four challenges described above. However, in some applications, where a limited set of fractional values are still useful, code can implicitly interpret the binary point to be elsewhere! Arithmetic routines can be easily implemented to manipulate the virtual binary point which can provide the foundation for lightning fast calculations. Search for Integer Math in C and enjoy the concept.

To prepare yourself for integer math manipulation, this challenge assumes the binary point is between bit 3 and bit 2 so that only 5 bits (bit 7 to bit 3) contribute to the integer part, leaving 3 bits (bit 2 to bit 0) to provide the fractional part. Under this design we say the range of numbers has a resolution of 1/8 or 0.125. For example, under Q(5.3), the binary representation of 6.875 would be 00110 111 and the representation of 17.375 would be 10001 011.

A further complication for Q(5.3) on our Binary Challenge device is that the VALUE display is only capable of presenting 4 digits (and a decimal point course). So, of the 256 possible configurations of 8 bits, weare limited to those that represent decimal equivalents that require only 4 digits to display. Thus, 6.875 is included but 17.375 is not. This still leaves 168 valid presentatations (more than enough to confirm you understand:).


C. D'Arcy. August 2019.