Unit 2 revison notes

CPU architectures:
von numen
Harvard

Memory configurations:
UMA
NUMA(edited)

registers:
accumulator in the ALU
CIR writes to the MAR
MAR goes along the system Bus, to RAM
Then gets called, so is taken out of RAM down the system bus
then gets executed and the register is cleared(edited)
interrupts are used when making calls to the CPU and halts execution(edited)
simplex - data can only be transferred one way
half duplex -data can be shared between both machines but only one way at a time
full duplex - data ca be sent between 2 machines both can send and revive at the same time
point to point - direct communication between 2 systems
multi-drop - communication from one machine to many others

compression:
lossy - is used on files which can have some of the details cut off, such as MP3's
lossless - has none of the data cut, this is used on files such as documents


error detection:
parity biits
Checksums
CRC checks
repition

error correction:
ARQ (automatic repeat request)
FEC (Froward error correction)


boolen logic:
AND gates: a | b | AB
           0 | 1 | 0
           1 | 0 | 0
           0 | 0 | 0
           1 | 1 | 1


OR gates: A  |  b  | AB
          1  |  0  |  1
          0  |  1  |  1
          1  |  1  |  1


NOT gates:  A | B
            1 | 0
            0 | 1


NAND gates: A | B | AB
            0 | 0 |  1
            1 | 0 |  1
            0 | 1 |  1
            1 | 1 |  0

NOR:        A  |  B  |  AB
            1  |  1  |  0
            1  |  0  |  0
            0  |  1  |  0
            0  |  0  |  1

XOR:       A |  B  |  AB
           0 |  0  |  0
           1 |  0  |  1
           0 |  1  |  1
           1 |  1  |  0