Monday, August 3rd

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Monday, August 3rd

• Program 4
• Due Friday, August 15th

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Quiz 3

• Thursday, February 28, in class
• Multiple-choice and short-answer
• Covers
• Tanenbaum
• chapters 3.1 3.4, 4.1 4.2
• Lectures 12 - 15
• Homework 2
• Program 3
• Calculator and one 4x6 notecard permitted
• No sharing

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Quiz 3

• 25 MASM
• system stack, parameter passing
• boolean instructions
• 75 circuits and micro-architecture (diagrams and
  instruction sets will be given)
• Gates, circuits
• Boolean functions/identities, truth tables
• Buses
• Memory hierarchy
• Peripheral devices
• Mic-1, IJVM
• Micro-instructions

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Today's topics

• IJVM
• Homework 2 (solutions will be posted)

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IJVM

• "Integer" Java Virtual Machine
• Forms basis for an assembly language
• Add directives, labels, etc., to make a
  "complete" language
• Implements the Mic-1 Instruction Set Architecture
  (ISA)

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IJVM instruction set
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Mic-1 architecture
The data path
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Complete block diagram for Mic-1
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Components of example MIR

• Addr address of next micro-instruction
• JAM jump address "management"
• JMPC conditional jump
• JMPN "negative"
• JMPZ "zero"
• Note N Z P ("positive")
• ALU ALU and Shifter function selector
• C selects registers to write from C bus
• Mem selects memory function
• read, write, fetch
• B selects register to read onto B bus

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• Complete instruction set for the Mic-1
  architecture.
• Any of these may be extended by appending
• ltlt8 (SLL8) to shift the result left by one byte.
• e.g., H MBR ltlt 8
• gt1 (SRA1) to shift the result right by one bit.
• e.g., H MBR gt1
• rd or wr or fetch
• e.g., DESTSOURCErd
• goto label
• e.g., DESTSOURCEgoto iadd2

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Mic-1 ISA

• Each "mnemonic" is a subprogram made of
  micro-instructions i.e., a micro-program
• Each micro-program is hard-wired as a circuit
• Note that all microprograms end with
• goto Main1
• which fetches the next instruction.
• Here is the complete set of IJVM micro-programs

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Addenda

• rd means to copy the contents of the memory
  location whose address is in MAR destination is
  MDR
• wr means to copy the contents of MDR
  destination is the memory location whose address
  is in MAR
• goto means set the micro-program counter (MPC)
  to the specified address in the control store.

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Virtual registers

• Z and N
• virtual registers status bits that get set by
  the ALU.
• Any operation that uses the ALU will set / clear
  the Z bit and the N bit
• Examples
• N OPC if (N) goto T else goto F
• Z OPC if (Z) goto T else goto F

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Virtual registers

• Z ltsourcegt means
• test the value in source
• set the Z status to 1 if the test result is zero
• set the Z status to 0 if the test result is not
  zero
• IF (Z) ltcommandgt means
• do the command if the Z status is 1.
• N ltsourcegt means
• test the value in source
• set the N status to 1 if the test result is
  negative
• set the N status to 0 if the test result is not
  negative
• IF (N) ltcommandgt means
• do the command if the N status is 1.

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• Questions on IJVM / Mic-1 ?
• Look at Homework 2

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Problem 2

• In the Mic-1, it takes 1 ns to set up the MIR, 1
  ns to gate a register onto the B bus, 3 ns to run
  the ALU and shifter, and 1 ns for the results to
  propagate back to the registers. The clock pulse
  width is 2 ns.
• a) Can this machine run at 100 MHz?
• b) Can this machine run at 150 MHz?

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Problem 3

• In the Mic-1, the B bus register is encoded in a
  4-bit field, but the C bus is represented as a
  bit-map. Why?

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Problem 7

• Do one IJVM translation of the following Java
  statement i j k 4

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Problem 8

• Give a Java statement that could have produced
  the following IJVM code
• ILOAD j
• ILOAD k
• ISUB
• BIPUSH 6
• ISUB
• DUP
• IADD
• ISTORE i

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Problem 10

• In if_cmpeq3 of the microprogram for the
  Mic-1, MDR is copied to H, and then TOS is
  subtracted from it in the next line if_cmpeq3 HM
  DRrd if_cmpeq4 OPCTOS
• Surely it is better to have just one statement
  here
• if_cmpeq3 ZMDR-TOSrd
• Why is this not done?

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Problems 14, 15

• 14 a) What is the arithmetic operation
  equivalent to shifting right with a count of 2?
• 15 a) What is the arithmetic operation
  equivalent to shifting left with a count of 2?

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• In the following Mic-1 microprogram, N and Z are
  virtual registers, i.e., they arent really
  registers, but they provide a notation for test
  instructions.
• mys1 MAR SP SP-1 rd
• mys2 Z TOS if(Z) goto mys5
• mys3 Z MDR if(Z)) goto mys5
• mys4 N TOS if(N) goto mys6 else goto mys8
• mys5 MDR TOS 0 wr goto main1
• mys6 MDR -MDR
• mys7 TOS -TOS
• mys8 H MDR
• mys9 TOS TOS-1 if(Z) goto mys11
• mys10 MDR MDRH goto mys9
• mys11 TOS MDR wr goto main1
• a) Assuming that a, and then b have been pushed
  onto the stack. a contains 5, and b contains -3.
  Fill in the instruction number at the top of the
  table, and show all of the changes in the
  specified registers and memory during the
  execution of each instruction.
• _at_ signifies "memory address of". _at_S means
  memory address of top of stack. ( ) indicate a
  "virtual" register (actually a status bit). ?
  means "undefined" or "doesn't matter".

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• What new instruction does the microprogram
  implement? (Its called mys for now, and
  comments are omitted so the problem won't be too
  easy.) Give the instruction an appropriate name
  and description as in figure 4.11 in the
  Tanenbaum textbook.

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Questions?

• Program 3 is due Thursday before midnight
• Quiz 3 Thursday in class