Ask the right questions to secure the right Ca65 talent among an increasingly shrinking pool of talent.

Ca65 is an advanced assembler for the 6502, 65C02, and 65816 microprocessors. It is part of the CC65 suite of programming tools, which also includes a compiler and linker. Ca65 supports a wide range of directives for data storage, macros, conditional assembly, and more. It also supports local and global symbols, as well as complex expressions. The assembler is capable of producing object files in O65 format or raw binary files. It is widely used for developing software for retro systems such as the Commodore 64 or Nintendo Entertainment System.

First 20 minutes

General Ca65 knowledge and experience

The next 20 minutes of the interview should attempt to focus more specifically on the development questions used, and the level of depth and skill the engineer possesses.

What are the key features of Ca65?

Key features of Ca65 include support for all 6502, 65C02, and 65816 instructions, a powerful macro language, and support for binary include files and structured programming.

Describe the difference between absolute and relative addressing in Ca65.

Absolute addressing in Ca65 refers to a specific memory location, whereas relative addressing refers to a location relative to the current program counter.

How would you set up a development environment for Ca65?

To set up a development environment for Ca65, you'll need a text editor, the CC65 compiler suite (which includes the Ca65 assembler), and an emulator for the target system.

What are the primary uses of Ca65?

Primarily, Ca65 is used for programming 6502-based microcomputers and video game consoles. It's also used in embedded systems and homebrew game development.

How would you define the role of a Ca65 developer?

A Ca65 developer is responsible for writing, testing, and debugging code in the Ca65 assembly language. They also optimize code for performance, maintain documentation, and collaborate with other team members on larger projects.

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What youre looking for early-on

Does the candidate show a willingness to learn and adapt?

The tech industry is constantly evolving. A good candidate should show a willingness to learn new skills and adapt to new technologies.

Has the candidate shown an ability to work within a team?

Most development projects require teamwork. The candidate should demonstrate that they can collaborate effectively with others.

Does the candidate have experience with other relevant technologies?

While Ca65 is the main focus, experience with other relevant technologies can be a strong indicator of a well-rounded and adaptable developer.

Is the candidate able to communicate effectively?

Communication is key in a development role. They must be able to articulate their ideas and solutions clearly and effectively.

Has the candidate demonstrated problem-solving skills?

Problem-solving is a key skill for any developer. They should be able to demonstrate how they would approach and solve a complex problem.

Does the candidate have a deep understanding of the Ca65 assembler?

This is crucial as the Ca65 assembler is the primary tool they will be using in their role. They should be able to demonstrate a high level of proficiency.

Next 20 minutes

Specific Ca65 development questions

The next 20 minutes of the interview should attempt to focus more specifically on the development questions used, and the level of depth and skill the engineer possesses.

What are the challenges of programming in Ca65 and how would you overcome them?

Challenges of programming in Ca65 include the complexity of assembly language and the limited resources of 6502-based systems. Overcoming these challenges requires a deep understanding of the 6502 architecture and careful planning and optimization.

How would you optimize code in Ca65?

Optimizing code in Ca65 involves strategies like minimizing memory usage, reducing the number of instructions, and taking advantage of the 6502's unique instruction set and addressing modes.

Describe the difference between JMP and JSR in Ca65.

In Ca65, JMP (Jump) is used to change the program counter to a new location, while JSR (Jump to SubRoutine) is used to call a subroutine, saving the return address on the stack.

What are the benefits of using Ca65 over other assemblers?

Benefits of using Ca65 include its powerful macro language, its support for all 6502 variants, and its integration with the CC65 compiler suite, making it easier to mix assembly and C code.

How would you debug a Ca65 program?

Debugging a Ca65 program typically involves using a 6502 debugger or emulator with debugging capabilities. The developer would set breakpoints, step through the code, and inspect memory and registers to identify errors.

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At this point, a skilled Ca65 engineer should display proficiency in assembly language, understanding of 6502/65816 microprocessors, and expertise in debugging. Red flags would include lack of practical experience or difficulty articulating complex concepts clearly.

Digging deeper

Code questions

These will help you see the candidate's real-world development capabilities with Ca65.

What does this simple piece of CA65 assembly code do?LDA #$00
STA $0200
This code loads the accumulator with the value 0 (LDA #$00), then stores the value in the accumulator to the memory address $0200 (STA $0200).
What will be the output of this CA65 assembly code?LDA #$01
BEQ skip
LDA #$02
skip: STA $0200
The output will be 2. The code loads the accumulator with the value 1, then checks if it is equal to zero. If it is, it skips the next instruction. Since it is not, it loads the accumulator with the value 2, then stores that value in the memory address $0200.
What does this CA65 assembly code do, which manipulates an array of data?LDX #$00
loop: LDA array,X
STA $0200,X
INX
CPX #$10
BNE loop
This code copies the first 16 bytes of data from an array to the memory addresses starting at $0200. It uses the X register as an index to loop through the array.
What does this CA65 assembly code do, which uses the IRQ interrupt?SEI
LDA #$34
STA $FFFE
CLI
This code sets the IRQ interrupt vector to the address $0034. It first disables interrupts (SEI), then stores the low byte of the address to the interrupt vector ($FFFE), and finally re-enables interrupts (CLI).
What does this CA65 assembly code do, which defines a simple object?.STRUCT object
property1: .BYTE
property2: .WORD
.ENDSTRUCT
This code defines a structure called 'object' with two properties. 'property1' is a byte in size, and 'property2' is a word in size.
What will be the output of this advanced piece of CA65 assembly code?LDX #$00
LDY #$00
loop: LDA array,X
CLC
ADC array2,Y
STA $0200,X
INX
INY
CPX #$10
BNE loop
This code adds together the values in two arrays, 'array' and 'array2', and stores the results in the memory addresses starting at $0200. It uses the X and Y registers as indices to loop through the arrays. The output will be the sum of the corresponding elements in 'array' and 'array2'.

Wrap-up questions

Final candidate for Ca65 role questions

The final few interview questions for a Ca65 candidate should typically focus on a combination of technical skills, personal goals, growth potential, team dynamics, and company culture.

Describe the difference between the 6502, 65C02, and 65816 processors and how this affects programming in Ca65.

The 6502, 65C02, and 65816 are different variants of the 6502 processor, each with their own instruction set and features. The 65C02 adds several new instructions and addressing modes, while the 65816 adds 16-bit registers and a larger address space. Programming in Ca65 involves understanding these differences and using the appropriate instructions and addressing modes for the target processor.

How would you approach writing a game in Ca65?

Writing a game in Ca65 would involve planning the game logic and graphics, writing the main game loop and input handling routines, and optimizing the code for performance and memory usage.

What are the best practices for writing clean and maintainable code in Ca65?

Best practices for writing clean and maintainable code in Ca65 include using meaningful labels and comments, following a consistent coding style, and making use of subroutines and macros to avoid repeating code.

Describe the difference between zero page and absolute addressing in Ca65.

In Ca65, zero page addressing refers to the first 256 bytes of memory, which can be accessed more quickly and with shorter instructions than other memory locations. Absolute addressing can refer to any location in memory.

How would you handle a large project in Ca65?

Handling a large project in Ca65 would involve breaking the project down into smaller, manageable components, making extensive use of subroutines and macros, and maintaining thorough documentation.

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Ca65 application related

Product Perfect's Ca65 development capabilities

Beyond hiring for your Ca65 engineering team, you may be in the market for additional help. Product Perfect provides seasoned expertise in Ca65 projects, and can engage in multiple capacities.

Ca65 Consultive assessments

Ca65 Application Conversion Assessment Ca65 Application Integration Assessment Ca65 Data & Database Integration Assessment

Custom Ca65 development projects

Custom Ca65 App Conversion Ca65 Custom App Development Process App UI Design for Ca65 Facelifts

Ca65 Developer Hiring Guide

Hiring Guide for Ca65 Engineers

First 20 minutes

General Ca65 knowledge and experience

What are the key features of Ca65?

Describe the difference between absolute and relative addressing in Ca65.

How would you set up a development environment for Ca65?

What are the primary uses of Ca65?

How would you define the role of a Ca65 developer?

What youre looking for early-on

Does the candidate show a willingness to learn and adapt?

Has the candidate shown an ability to work within a team?

Does the candidate have experience with other relevant technologies?

Is the candidate able to communicate effectively?

Has the candidate demonstrated problem-solving skills?

Does the candidate have a deep understanding of the Ca65 assembler?

Next 20 minutes

Specific Ca65 development questions

What are the challenges of programming in Ca65 and how would you overcome them?

How would you optimize code in Ca65?

Describe the difference between JMP and JSR in Ca65.

What are the benefits of using Ca65 over other assemblers?

How would you debug a Ca65 program?

The ideal back-end app developer

What you’re looking to see on the Ca65 engineer at this point.

What does this simple piece of CA65 assembly code do?

This code loads the accumulator with the value 0 (LDA #$00), then stores the value in the accumulator to the memory address $0200 (STA $0200).

What will be the output of this CA65 assembly code?

The output will be 2. The code loads the accumulator with the value 1, then checks if it is equal to zero. If it is, it skips the next instruction. Since it is not, it loads the accumulator with the value 2, then stores that value in the memory address $0200.

What does this CA65 assembly code do, which manipulates an array of data?

This code copies the first 16 bytes of data from an array to the memory addresses starting at $0200. It uses the X register as an index to loop through the array.

What does this CA65 assembly code do, which uses the IRQ interrupt?

This code sets the IRQ interrupt vector to the address $0034. It first disables interrupts (SEI), then stores the low byte of the address to the interrupt vector ($FFFE), and finally re-enables interrupts (CLI).

What does this CA65 assembly code do, which defines a simple object?

This code defines a structure called 'object' with two properties. 'property1' is a byte in size, and 'property2' is a word in size.

What will be the output of this advanced piece of CA65 assembly code?

This code adds together the values in two arrays, 'array' and 'array2', and stores the results in the memory addresses starting at $0200. It uses the X and Y registers as indices to loop through the arrays. The output will be the sum of the corresponding elements in 'array' and 'array2'.

Wrap-up questions

Final candidate for Ca65 role questions

Describe the difference between the 6502, 65C02, and 65816 processors and how this affects programming in Ca65.

How would you approach writing a game in Ca65?

What are the best practices for writing clean and maintainable code in Ca65?

Describe the difference between zero page and absolute addressing in Ca65.

How would you handle a large project in Ca65?

Ca65 Consultive assessments

Custom Ca65 development projects