Review for Midterm 1

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Review for Midterm 1

• CPSC 321 Computer Architecture
• Andreas Klappenecker

2
Administrative Issues

• Office hours have been moved
• Wednesday October 15 and 22 canceled
• Thursday October 16 and 23 _at_ 200pm-300pm
• Talk by Bjarne Stroustrup
• today _at_ 410pm, HRBB 124

3
Reading Assignments

• Chapter 1,2,3,4, Appendix B
• How does the algorithm work?
• What is the complexity of the algorithm?
• Work some examples
• Get familiar with number representations
• Assembly programming, the gory details
• Combinatorial circuits
• Read keyword list first, then the chapter

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Early History

• 1938 Zuses Z1
• electromechanical, experimental
• Zuses Z2 almost identical to Z1
• 1941 Zuses Z3
• first reliable, freely programmable computer
• memory based on relays
• did not have stored program concept
• Turing-complete

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Early History

• 1943-44 Mark 1 Colossus
• memory based on vacuum tubes
• special purpose machine, not Turing complete
• but it had some flexibility
• used in Bletchley Park to break the fish cipher

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Early History

• 1944 Harvard Mark I by Aiken and team
• decimal number system
• memory based on relays
• 1945 ENIAC by Eckert and Mauchly
• memory based on vacuum tubes
• 1945 von Neumann et al.
• introduce the stored program principle
• incorporated in EDVAC design

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Questions

• How was the memory of xyz realized?
• Was xyz Turing-complete?
• Who designed xyz?

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MIPS Assembly Language

• Complete a template program
• What does the code fragment do?
• Stack usage for recursive procedures
• know every nut, bolt and screw
• slightly different skills needed
• Know your pseudoinstructions
• Is blt a,b,c an instruction?

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MIPS Addressing Modes

• Immediate addressing
• Register addressing
• Base displacement addressing
• PC-relative addressing
• address is the sum of the PC and a constant in
  the instruction
• Pseudo-direct addressing
• jump address is 26bits of instruction
  concatenated with upper bits of PC

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Addressing Modes

• Register Addressing
• add s1, s2, s3
• s1 s2 s3
• Immediate Addressing
• addi s1, s2, 100
• s1 s2 100

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Addressing Modes

• Base addressing
• lw s1, 100(s2)
• s1 Memorys2100
• PC-relative branch
• beq s1, s2, 25
• if (s1 s2) goto PC 4 100

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Addressing Modes

• Pseudo-direct addressing
• j 1000
• goto 1000
• concatenate 26bit address with upper bits of the
  PC
• Study section 3.8 for further details
• In particular, get used to Figure 3.18

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Arithmetic

• Know how to add and subtract
• Know when overflow occurs
• Be able to construct an ALU
• or something like that
• Carry lookahead

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Idea of Carry Lookahead
coutabcin(a xor b) abacinbcin
ab(ab)cin g p cin Generate g
ab Propagate p ab
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Carry Lookahead

• Iterate the idea, generate and propagate
• ci1 gi pici
• gi pi(gi-1 pi-1 ci-1)
• gi pigi-1 pipi-1ci-1
• gi pigi-1 pipi-1gi-2 pipi-1 p1g0
• 
  pipi-1 p1p0c0
• Two level AND-OR circuit
• Carry is known early!

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Booths Multiplication

• Looking at 2 bits of multiplier
• If the bits are
• 00 gt do nothing
• 10 gt beginning run of 1s subtract
• 01 gt end of run of 1s add
• 11 gt do nothing

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Booths Multiplication

• Multiply 0010 by 0110 00001100
• 0000
• 00100 sub add 11111100
• 000000
• 0010000 add add 00010000
• 0001100

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Floating Point

• Know the IEEE 754 representation
• sign bit s
• exponent E with 8 bits
• significand S with 23 bits
• bias 127
• (-1)s x (1S)x2(E-127)
• Given 32 bits, interpret
• Know all conversions

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Final Remarks

• Use exercises at end of chapter to check
  knowledge
• Answers are usually easy to figure out with the
  help of the text
• Do not cheat! Read the text carefully, then
  attempt to solve the problems
• Appendices A and B are useful bedtime reading
• There is a need for speed!