Difference between revisions of "Instructions"
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| + | An instruction can be split into 2 parts, the command to use and the data to use for the command. | ||
<youtube>https://www.youtube.com/watch?v=2h3hQCV3YcE&index=117&list=PLCiOXwirraUDUYF_qDYcZV8Hce8dsE_Ho</youtube> | <youtube>https://www.youtube.com/watch?v=2h3hQCV3YcE&index=117&list=PLCiOXwirraUDUYF_qDYcZV8Hce8dsE_Ho</youtube> | ||
Revision as of 08:48, 11 June 2018
Contents
Overview
An instruction can be split into 2 parts, the command to use and the data to use for the command.
https://www.youtube.com/watch?v=2h3hQCV3YcE&index=117&list=PLCiOXwirraUDUYF_qDYcZV8Hce8dsE_Ho
OpCode
The command for the instruction, ie Load, Store, Add
Operand
The data to be used by the OpCode, this can be data eg #21 (ie the number 21) or it can be an address eg 21 (ie memory location 21)
Addressing
https://www.youtube.com/watch?v=yKNrFfVdu3g&list=PLCiOXwirraUDUYF_qDYcZV8Hce8dsE_Ho&index=120
Immediate Addressing
The operand is data eg #21
Direct Addressing
The operand is a location eg 21
Indirect Addressing - not in AQA Specification
The operand is a location which contains the location for the instruction
Index Addressing - not in AQA Specification
The operand is the number in the Index Regisiter after the location in the instruction
