Computer Architecture Flashcards
Describe what these types of Registers do.
Register A:
Register B:
Register RO-RN:
Temp Registers:
Register A: Accumulator- Operands being manipulated.
Register B: Used as an extension to the A register.
Registers RO-RN: Used by the programs under execution.
Temp Registers: used by the processors operations.
Describe what these types of Special Registers do:
Status Flags:
Memory Address Register (MAR):
Memory Data Register (MDR):
Status Flags: Refers to bits within a special register. Can be set (have a value of 1) to designate a situation. E.g., if the result of an operation was 0, the “Z” flag is set.
Memory Address Register (MAR): Links internal buses to the external Address bus. All address’ are passing through this register.
Memory Data Register (MDR): Links internal buses to the external Data bus. All data is passing through this register.
How do you convert a positive binary to a negative binary using 2’s compliment?
For example: 00010100= 20
Find least significant bit (non zero).
00010[1]00
Keep everything up until this bit. But flip the rest.
Answer: 11101100 = -20.
Convert 30 in binary to -30.
Answer:
30 = 00011110
-30= 11100010
How would you do a minus sum using binary numbers, one of which being a negative binary number?
Add both binary combinations together like normal, but REMOVE any left over remainders!!
What is the truth table for NOT? (Boolean algebra).
A Ā
0 1
1 0
-One, NOT the other basically.
What is the truth table for AND? (Boolean algebra).
A B AB 0 0= 0 1 1= 1 1 0= 0 0 1= 0
Basically, BOTH A AND B must be active.
What is the truth table for OR? (Boolean algebra).
A B AB 0 0 =0 1 0 =1 0 1 =1 1 1 =0
One OR the other. OR is exclusive, meaning 1-1 does not activate. XOR is inclusive, meaning 1-1 does activate.
What is the truth table for XOR? (Boolean Algebra).
0 0 =0
1 0 =1
0 1 =1
1 1 =1
One OR the other, but also BOTH. XOR, unlike OR, is inclusive, meaning 1-1 will activate.
Describe the PARALLEL type of I/O.
- All data is transferred parallel, at the same time.
- Adapter will channel all bits across I/O at the same time.
- Expensive, very big, so may not fit into some computer systems.
- Very Fast
Describe the SERIEL type of I/O
- Bits transferred one after the other.
- Adapter will channel all bits across one at a time.
- Slower than parallel.
Describe the ANALOGUE type of I/O.
- Data is converted from analogue to digital (converted to binary).
- Analogue data is measured in waves, so when being converted, the computer must occasionally test the value of the wave.
- Bigger waves mean more complicated and longer conversions.
- Once analogue data has been measured it vanishes.
What is the purpose of the Address Decoder?
-Allows addressing of multiple memory and I/O chips but is using a single address to identify both.
What does DMAC do?
-Facilitates data transfers between I/O chips without involving the processor, this is more efficient.
