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CHIP-8 is an interpreted programming language, developed in the mid-1970s by Joseph Weisbecker. Originally designed for the 8-bit microcomputer COSMAC VIP, it became a popular tool for video game creation during early home computing era. The language allows developers to write highly efficient games with minimal coding effort on resource-constrained devices. Notably, CHIP-8 programs are run on a virtual machine, making them compatible across various hardware platforms. Today, it serves as an educational tool due to its simplicity and wide usage in retro-computing circles (source: Wikipedia).

Ask the right questions secure the right CHIP-8 talent among an increasingly shrinking pool of talent.

First 20 minutes

General CHIP-8 app knowledge and experience

The first 20 minutes of the interview should seek to understand the candidate's general background in CHIP-8 application development, including their experience with various programming languages, databases, and their approach to designing scalable and maintainable systems.

How would you describe the architecture of CHIP-8?

CHIP-8 has a simple architecture with 4K of memory, 16 8-bit data registers, one 16-bit address register, two timers and a stack.

What are the main components of a CHIP-8 emulator?

The main components of a CHIP-8 emulator include the CPU, memory, display, keyboard, timers, and a sound generator.

Describe the difference between the original CHIP-8 and Super CHIP-8.

Super CHIP-8 is an extended version of the original CHIP-8. It has additional instructions and supports a higher resolution display.

How would you implement the CHIP-8 timers?

CHIP-8 has two timers, a delay timer and a sound timer. They both count down at 60 Hz. When the sound timer reaches zero, a beep is produced.

What are the main challenges in developing a CHIP-8 emulator?

The main challenges include accurately emulating the original hardware, handling user input, and synchronizing the timers with the system clock.

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What you’re looking for early on

Does the candidate have a solid understanding of the CHIP-8 language?

Has the candidate demonstrated problem-solving skills?

Is the candidate able to communicate effectively?

Does the candidate have experience with other programming languages?

Next 20 minutes

Specific CHIP-8 development questions

The next 20 minutes of the interview should focus on the candidate's expertise with specific backend frameworks, their understanding of RESTful APIs, and their experience in handling data storage and retrieval efficiently.

How would you handle user input in a CHIP-8 emulator?

User input is handled by mapping the CHIP-8's 16-key hexadecimal keyboard to the keys on the modern keyboard.

Describe the difference between the CHIP-8 instruction set and the instruction set of a modern CPU.

The CHIP-8 instruction set is much simpler and smaller than the instruction set of a modern CPU. It only has 35 instructions, while a modern CPU has hundreds of instructions.

How would you implement the CHIP-8 display?

The CHIP-8 display is a 64x32 pixel monochrome display. It can be implemented using a 2D array of boolean values.

What are the main steps in the execution cycle of a CHIP-8 emulator?

The main steps are fetching the next instruction, decoding the instruction, executing the instruction, updating the timers, and updating the display.

How would you handle the CHIP-8 sound generator?

The CHIP-8 sound generator produces a beep when the sound timer reaches zero. This can be implemented using a simple square wave generator.

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At this point, a skilled CHIP-8 engineer should demonstrate strong problem-solving abilities, proficiency in CHIP-8 programming language, and knowledge of software development methodologies. Red flags include lack of hands-on experience, inability to articulate complex concepts, or unfamiliarity with standard coding practices.

Digging deeper

Code questions

These will help you see the candidate's real-world development capabilities with CHIP-8.

What does this simple CHIP-8 instruction do: '6XNN'?
6001
This instruction sets the value of register VX to 01.
What does the following CHIP-8 instruction do: 'FX29'?
F029
This instruction sets the I register to the location of the sprite for the character in register VX.
What does the following CHIP-8 instruction do: 'FX33'?
F033
This instruction stores the binary-coded decimal representation of the value in register VX at addresses I, I+1, and I+2.
What does the following CHIP-8 instruction do: 'FX0A'?
F00A
This instruction waits for a key press and stores the result in register VX.

Wrap-up questions

Final candidate for CHIP-8 Developer role questions

The final few questions should evaluate the candidate's teamwork, communication, and problem-solving skills. Additionally, assess their knowledge of microservices architecture, serverless computing, and how they handle CHIP-8 application deployments. Inquire about their experience in handling system failures and their approach to debugging and troubleshooting.

Describe the difference between the CHIP-8 memory layout and the memory layout of a modern computer.

The CHIP-8 memory layout is much simpler than the memory layout of a modern computer. It only has 4K of memory, while a modern computer has gigabytes of memory.

How would you implement the CHIP-8 stack?

The CHIP-8 stack is used for subroutine calls. It can be implemented using an array and a stack pointer.

What are the main considerations when porting a CHIP-8 emulator to a different platform?

The main considerations include handling user input, synchronizing the timers with the system clock, and implementing the display and sound generator.

CHIP-8 application related

Product Perfect's CHIP-8 development capabilities

Beyond hiring for your CHIP-8 engineering team, you may be in the market for additional help. Product Perfect provides seasoned expertise in CHIP-8 projects, and can engage in multiple capacities.

CHIP-8 Consultive assessments

CHIP-8 Application Conversion Assessment CHIP-8 Application Integration Assessment CHIP-8 Data & Database Integration Assessment

Custom CHIP-8 development projects

Custom CHIP-8 App Conversion CHIP-8 Custom App Development Process App UI Design for CHIP-8 Facelifts

Hiring guide for CHIP-8 Engineers

CHIP-8 Developer Hiring Guide

What you’re looking for early on

The ideal back-end app developer

What you’re looking to see on the CHIP-8 engineer at this point.

CHIP-8 Consultive assessments

Custom CHIP-8 development projects