Hiring guide for BAL (Basic Assembly Language) Engineers

BAL (Basic Assembly Language) Developer Hiring Guide

The Basic Assembly Language (BAL) is a low-level programming language developed by IBM for its mainframe computers, including the IBM 360 and System/370 series. Introduced in the mid-1960s, BAL was designed to directly manipulate hardware and system resources, offering programmers a high degree of control over the machine's operations. It was primarily used for systems programming and scientific computations due to its efficiency in handling large volumes of data. Despite being largely superseded by higher-level languages today, BAL remains an essential part of computing history as one of the earliest assembly languages. Information sourced from "IBM's 360 and Early 370 Systems" by Emerson W Pugh et al., MIT Press.

Ask the right questions secure the right BAL (Basic Assembly Language) talent among an increasingly shrinking pool of talent.

First 20 minutes

General BAL (Basic Assembly Language) app knowledge and experience

The first 20 minutes of the interview should seek to understand the candidate's general background in BAL (Basic Assembly Language) application development, including their experience with various programming languages, databases, and their approach to designing scalable and maintainable systems.

What are the basic components of a BAL program?
The basic components of a BAL program include the START, END, USING, and LTORG directives, as well as the instructions for the program.
How would you define an instruction in BAL?
An instruction in BAL is a statement that tells the computer to perform a specific operation. It consists of an operation code, and may also include one or more operands.
Describe the difference between the LOAD and STORE instructions in BAL.
The LOAD instruction is used to load data from memory into a register, while the STORE instruction is used to store data from a register into memory.
What is the purpose of the USING directive in BAL?
The USING directive is used to establish a base register and a base address for addressing purposes. It helps in simplifying the addressing of memory.
How would you handle errors in a BAL program?
Errors in a BAL program can be handled using various techniques such as checking for error codes after each operation, using the CHECK instruction to test for specific conditions, or using the TRAP instruction to handle exceptional conditions.
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What you’re looking for early on

Has the candidate demonstrated a strong understanding of Basic Assembly Language?
Is the candidate able to solve problems using BAL?
Does the candidate show a capacity to learn and adapt?
Has the candidate demonstrated experience with debugging in BAL?

Next 20 minutes

Specific BAL (Basic Assembly Language) 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.

What are the different types of addressing modes in BAL?
The different types of addressing modes in BAL include direct addressing, indirect addressing, immediate addressing, and relative addressing.
Describe the difference between immediate and direct addressing in BAL.
In immediate addressing, the operand is a constant value that is part of the instruction itself. In direct addressing, the operand is a memory address, and the instruction refers directly to the memory location.
How would you implement a loop in BAL?
A loop in BAL can be implemented using the BRANCH instruction. The condition for the loop can be checked using the COMPARE instruction, and the BRANCH instruction can be used to jump back to the start of the loop if the condition is true.
What is the purpose of the LTORG directive in BAL?
The LTORG directive is used to tell the assembler to place the literals used in the program in memory. It helps in managing the literals in a BAL program.
How would you perform arithmetic operations in BAL?
Arithmetic operations in BAL can be performed using the ADD, SUBTRACT, MULTIPLY, and DIVIDE instructions. These instructions operate on the contents of registers and/or memory locations.
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The ideal back-end app developer

What you’re looking to see on the BAL (Basic Assembly Language) engineer at this point.

At this point, a skilled BAL (Basic Assembly Language) engineer should demonstrate strong problem-solving abilities, proficiency in BAL (Basic Assembly Language) 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 BAL (Basic Assembly Language).

What does the following BAL code do? 'L 1,DATA1'
L 1,DATA1
This code loads the contents of the memory location labeled 'DATA1' into general purpose register 1.
What will be the output of the following BAL code? 'A 2,DATA2'
A 2,DATA2
The code adds the contents of the memory location labeled 'DATA2' to the contents of general purpose register 2. The result is stored in register 2.
What does the following BAL code do? 'ST 3,DATA3'
ST 3,DATA3
This code stores the contents of general purpose register 3 into the memory location labeled 'DATA3'.
What does the following BAL code do? 'B LOOP'
B LOOP
The code branches to the instruction labeled 'LOOP'. It is used for implementing loops and conditional constructs.

Wrap-up questions

Final candidate for BAL (Basic Assembly Language) 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 BAL (Basic Assembly Language) application deployments. Inquire about their experience in handling system failures and their approach to debugging and troubleshooting.

What are the different types of registers in BAL?
The different types of registers in BAL include general purpose registers, floating point registers, control registers, and access registers.
Describe the difference between the BRANCH and JUMP instructions in BAL.
The BRANCH instruction is used to transfer control to a different part of the program based on a condition, while the JUMP instruction is used to unconditionally transfer control to a different part of the program.
How would you implement a subroutine in BAL?
A subroutine in BAL can be implemented using the BALR (Branch and Link Register) instruction. This instruction saves the return address in a register, and then transfers control to the subroutine.

BAL (Basic Assembly Language) application related

Product Perfect's BAL (Basic Assembly Language) development capabilities

Beyond hiring for your BAL (Basic Assembly Language) engineering team, you may be in the market for additional help. Product Perfect provides seasoned expertise in BAL (Basic Assembly Language) projects, and can engage in multiple capacities.