Comp Sci LC3 ISA
LC-3 instructions, select the best description of what it does. "NOT"
Inverts each bit of a value stored in register.
If the condition code values are N=1, Z=0, and P=0, which of the below statements is true about the most recent operation that updated the condition codes?
Negative
If the condition code values are N=0, Z=0, and P=1, which of the below statements is true about the most recent operation that updated the condition codes?
Positive
If the condition code values are N=1, Z=0, and P=0, which of the below statements is true about the most recent operation that updated the condition codes?
The operation placed a negative value into a register.
If the condition code values are N=0, Z=1, and P=0, which of the below statements is true about the most recent operation that updated the condition codes?
Zero
What would be a good name for a signal connected to output 1 of the above decoder?
isADD
What would be a good name for a signal connected to output 5 of the above decoder?
isAND
The name of the signal connected to the output is named ____ because that output of the decoder is only 1 (true) when the instruction in the IR is a BR instruction, and is 0 (false) when the IR holds any other type of instruction that is not a BR instruction.
isBR
What would be a good name for a signal connected to output 9 of the above decoder?
isNOT
For a BR instruction, output ____ of the decoder will be equal to ____ and all other decoder outputs will be equal to ____.
0 1 0
A signal named isLDI should be connected to which decoder output?
10
A signal named isSTI should be connected to which decoder output?
11
The DR signal (connected to the DA input of the register file) comes from IR[______] but the value of that 3-bit signal only matters when writing to register.
11:9
A signal named isLD should be connected to which decoder output?
2
By looking at the ADD and AND instructions on the LC-3 Instruction Set sheet, we can see that the SR2 signal (the address of source register 2) should be connected to IR[____].
2:0
A signal named isST should be connected to which decoder output?
3
BMUX is value at position? (in ADD, AND, NOT)
5
A signal named isLDR should be connected to which decoder output?
6
A signal named isSTR should be connected to which decoder output?
7
By looking at the ADD and AND instructions on the LC-3 Instruction Set sheet, we can see that the SR1 signal (the address of source register 1) should be connected to IR[____].
8:6
LC-3 instructions, select the best description of what it does. "ADD"
Adds contents of two registers, or one register and one sign-extended constant.
LC-3 instructions, select the best description of what it does. "AND"
Bitwise ANDs values in two registers, or one register and one sign-extended constant.