Principles of computer composition
Original code inverse code complement code shift code
A positive number:
Original code = inverse code = complement code
Code shift: invert the sign bit of the complement code
negative number:
Original code -> Inverse code: the sign bit remains unchanged, and the rest of the bits are all inverted
Inverse code -> Complementary code: +1 on the basis of inverse code
Complement -> Shift: Invert the sign bit
Indicates the range:
8-bit case:
Original code: -127 ~ 127 In case of +0 and -0: 0000 0000 | 1000 0000
Inverse code: -127 ~ 127 In case of +0 and -0: 0000 0000 | 1111 1111
Complementary code: -128 ~ 127 +0 and -0 are both 8 0s, so one more bit can be represented: 0000 0000
floating point number
N = M*R^e, M is the mantissa, e is the exponent, and R is the base.
1.19 * 10^2, 1.19 is the mantissa, 2 is the exponent, and 10 is the base.
CPU structure (concept)
Flynn taxonomy (concept test)
CISC and RISC (concept test)
Pipeline computing (computing)
Find the pipeline cycle ▲t:
The pipeline cycle refers to the period with the longest execution time, here is 2ns
Find the pipeline execution time:
Theoretical formula (80% inspection):
Execution time = (t1+t2+...+tk)+(n-1)*▲t
Pipeline execution time: 1 instruction execution time + (number of instructions - 1) pipeline cycle *
(2ns+2ns+1ns)+(n-1)*2ns, when there are 100 instructions, 5ns+99*2ns = 203ns
Practical formula (20% inspection):
Execution time = (k+n-1) * ▲t
Pipeline execution time: (total part + number of instructions - 1) pipeline cycle *
（3+100-1）* 2ns = 204ns
Find the throughput rate TP of the pipeline
Throughput TP = number of instructions/pipeline execution time
= 100 bars / 203ns
Maximum throughput = 1 / pipeline cycle = 1 / ▲t
Find the speedup ratio S of the pipeline
The speedup ratio of the pipeline S = Execution time without pipeline / Execution time with pipeline
= (2ns + 2ns + 1ns) * 100 / 203ns
= 500 / 203ns
Find the efficiency E of the pipeline
Pipeline efficiency E = shaded part / total part
= (▲t + ▲t + ▲t + 3▲t) * 4 tasks / 15▲t * 4
= 24▲t / 60▲t
= 4 / 15
Random access memory and read-only memory (address units and bits are counted)
The working principle of the disk (the maximum and minimum time of scanning records will be calculated)
computer bus
Reliability Calculation of Series System and Parallel System
check code
Learn Yard Distance
The CRC cycle check code can only detect errors, but not correct them.
Hamming check codes can both detect and correct errors.
Learn to calculate cyclic checksum
Remember that it is a modulo 2 division, and each time it is an XOR operation.
Learn to Calculate Hamming Code
