1A sequence of instructions written in mnemonics specific to a microprocessor, designed to execute a specific task.
Assembly language program
2What are the two main parts of every Z80 instruction?
The Opcode (Operation Code) and the Operand.
3What does the Opcode specify?
It specifies what action to perform (the task).
4What does the Operand specify?
It specifies what data to use or where the data is located.
5In what format are Z80 instructions always stored?
Binary format.
6How do you determine the number of memory locations an instruction requires?
It is exactly equal to its instruction length in bytes.
7What is the standard syntax rule for specifying source and destination in Z80?
The destination is always specified first, and the source is specified second.
8What is the rule for storing 16-bit addresses or data in memory?
The low-order byte is stored first.
9What is the size range of Z80 instructions?
1 to 4 bytes.
10What is the structure of a 1-Byte instruction?
The Opcode and Operand are contained in the same byte.
11What are 1-Byte instructions typically used for?
Simple register-to-register operations.
12What is the structure of a 2-Byte instruction?
Byte 1 is the Opcode, and Byte 2 is the Operand (immediate 8-bit data).
13What is the structure of a 3-Byte instruction?
Byte 1 is the Opcode, and Bytes 2 & 3 are 16-bit Address/Data.
14What is the structure of a 4-Byte instruction?
Byte 1 is the Opcode Prefix, Byte 2 is the Main Opcode, and Bytes 3 & 4 are 16-bit Data.
15Which type of registers are 4-Byte instructions most commonly associated with?
Index registers.
16What happens to the original data in the source during a Data Copy or Load operation?
The original data remains unchanged.
17What does the PUSH BC instruction do?
It pushes the register pair BC to the stack.
18What instruction calculates the 1's complement of the accumulator?
CPL
19What instruction calculates the 2's complement of the accumulator?
NEG
20What does the instruction RRA do?
It rotates the accumulator right through the carry flag.
21What is the purpose of a Bit Test instruction?
To check if a specific bit is 0 or 1, which modifies the Z flag.
22What does the instruction SET 5, A do?
It forces bit D5 in the accumulator to 1.
23What is the primary function of Branch Operations?
To alter the sequential flow of the program.
24What is the purpose of Machine Control Operations?
To control the overall state of the processor.
25What does the HALT instruction do?
It suspends processor execution.
26What does the DI instruction do?
It disables interrupts.
27How many memory locations are required for an instruction?
The number of memory locations required is equal to the instruction length in bytes.
28What is the binary code for the LD A, B instruction?
01111000 (78H).
29What is the binary code for the ADD A, B instruction?
10000000 (80H).
30In a 4-byte instruction, what is the specific role of the first and second bytes?
Byte 1 is the opcode prefix and Byte 2 is the main opcode.
31When storing a 16-bit value like 2080H, which part is the "low-order" byte?
80H (representing bits A0 to A7).