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Intro to LC3 Processor
Quiz 5
35
Computer Science
Undergraduate 2
10/08/2015

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Cards

Term
What are the 3 types of instructions?
Definition
operate, data movement, control
Term
Process data (addition, logical operations, etc.)
Definition
Operate Instructions
Term
Move data between memory locations and registers
Definition
Data Movement Instructions
Term
Change the sequence of execution of instructions in the stored program
Definition
Control Instructions
Term
Phases of the complete Instruction Cycle
Definition
Fetch, decode, evaluate address, fetch operands, execute, store results
Term
Load IR with instruction from memory
Definition
Fetch
Term
Determine action to take (set up inputs for ALU, RAM, etc.)
Definition
Decode
Term
Compute memory address of operands, if any
Definition
Evaluate address
Term
Read operands from memory or registers
Definition
Fetch operands
Term
Carry out instruction
Definition
Execute
Term
Store results
Definition
Write result to destination (register or memory)
Term
_____ are unconditional -- always change the PC
Definition
Jumps
Term
_____ are conditional -- change the PC only if some condition is true
Definition
Branches
Term
Memory- Address Space: _____ locations (16-bit addresses), Addressability: _____ bits
Definition
2^16, 16
Term
Temporary storage, accessed in a single machine cycle
Definition
Registers
Term
How many general-purpose registers are there? How many bits is each?
Definition
8, 16
Term
What are the other registers?
Definition
PC (program counter), condition codes
Term
How many opcodes?
Definition
15
Term
Examples of non-memory addresses
Definition
immediate, register
Term
Examples of memory addresses
Definition
PC-relative, indirect, base+offset
Term
3 Operate Intrstructions
Definition
ADD, AND, NOT
Term
Source and destination operands of operate instructions are _____. These do not reference _____.
Definition
registers, memory
Term
1001 Dst Src 111111
Definition
NOT
Term
0001 DR SR1 0 00 SR2
0001 DR SR1 1 imm5
Definition
ADD
Term
0101 DR SR1 0 00 SR2
0101 DR SR1 1 imm5
Definition
AND
Term
Read data from memory to register
Definition
Load
Term
Write data from register to memory
Definition
Store
Term
Compute address, save in register
Definition
Load effective address
Term
What modes are LD, ST
Definition
PC-relative mode
Term
What modes are LDR, STR?
Definition
base+offset mode
Term
What modes are LDI, STI
Definition
Indirect mode
Term
What mode is LEA?
Definition
Immediate mode
Term
PC-Relative Addressing Mode: _____ bits for opcode, _____ bits for register, _____ bits available for address
Definition
4, 3, 9
Term
9 bits: -256 <= offset <= 255
Can form any _____ X, such that: PC-256 <= X <= PC+255
Definition
address
Term
What does MAR and MDR stand for?
Definition
Memory address register, memory data register
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