The Micro Architecture Level Mic-1 architecture on Tanenbaum’s book Dept. of Computer Science Virginia Commonwealth University

Mic-1 block diagram

1. Why the C bus is represented as a bit map? while B bus register is encoded in a 4 bit field Only one register can be loaded onto B bus, yet more than one register can be selected to be loaded from C bus

2. Give a circuit diagram for “High bit”. Simple answer? F =(JAMZ AND Z) OR (JAMN AND N) OR NEXT_ADDRESS[8]

Calculation of Next Address Z JAMZ N JAMN Addr8 MPC8 JAMC MBR7 Addr7 MPC7 MBR0 Addr0 MPC0 

Calculation of Next address MPC points to the next microinstruction. it is computed from Next_Address JAM fields the ALU status N and Z, the MBR If JMPC MPC[0:7] = Addr[0:7] Else Addr[0:7] OR MBR[0:7]. MPC[8] = Addr[8] or (JAMZ and Z) or (JAMN and Z)

Calculation of Next Address

3. Next address = 0x1FF and use JMPC? Does it make sense? What if Next address is 0xFF? 111111111 (Next Address) bbbbbbbb (MBR) No, Meaningless Next address is usually, 0x00 or 0x100 Why?

4. What if add k=5 after IF? K = 5 BIPUSH 5 ISTORE k

5 IJVM translation of i= k + n + 5 ILOAD k ILOAD n IADD BIOUSH 5 ISTORE i ILOAD k ILOAD n BIOUSH 5 IADD ISTORE i 5 n n+5 k k k k+n+5 n 5 k k k+n k+n k+n+5

6. Give the JAVA statement ILOAD j ILOAD n ISUB BIPUSH 7 DUP IADD ISTORE i i = j-n-7 + j-n-7 n 7 j-n-7 j j j-n j-n j-n-7 j-n-7 2(j-n-7)

7. Is it possible? If (Z) go to L1; else go to L2 // on page 259 0x75 Z : upper half or lower half

8.Why not: if_cmpeq3 Z = TOS-MDR;rd If_icmpeq1 MAR=Sp=Sp-1; rd If_icmpeq2 MAR=SP=SP-1 If_icmpeq3 H=MDR; rd If_icmpeq4 OPC = TOS If_icmpeq5 TOS = MDR If_icmpeq6 Z=OPC-H; if (Z) go to T; else go to F The only possible subtrahend is H

9. How long it will takes? i = j+ k; w/ 2.tGHz Mic1 Main PC = PC +1; fetch; go to (MBR) Iload1 H=LV Iload2 MAR=MBRU+H; rd Iload3 MAR=SP=SP+1 Iload4 PC = PC +; fetch; wr Iload5 TOS = MDR; go to main ILOAD j ILOAD k IADD ISTORE Main PC = PC +1; fetch; go to (MBR) ISTORE1 H=LV ISTORE2 MAR=MBRU+H ISTORE3 MDR=TOS; wr ISTORE4 SP=MAR=SP-1; wr ISTORE5 PC = PC +1; fetch ISTORE6 TOS = MDRT; goto main Main PC = PC +1; fetch; go to (MBR) IADD1 MAR=SP = SP-1; rd; IADD2 H=TOS IADD3 MDR = TOS+MDR-H;wr; goto main ILOAD(6) IADD(4) ISTORE(7) 23microinstructions *0.4nsec = 9.2 nsec 2.5GHz means 1 cycle / (1 / 2.5* G)sec = 0.4nanosec

Microinstruction

Microinstruction

Microinstruction: load k ILOAD K 0x15 0x03

Microinstruction: iadd IADD 0x60

Microinstruction: istore ISTORE I 0x36 0x01

Microinstruction: Homework by Nov 28

10 speed with Mic-2 Mic1 : 2 bus architecture Mic2 : simplified decoding, 3 bus, IFU Mic3 : 4 stage pipeline Mic4 : 7 state pipeline What is common? PC is passed through the CPU and incremented PC is used to fetch next byte Operands are read from memory Operand are written to memory ALU does computation and results are stored back IFU (Instruction Fetch Unit) Independently increment PC and fetch next byte (assemble 8 and 16 bit operands) Depends on the opcode make available the next 8 or 16 bit whether or not doing so makes sense.

Mic-2

How to design IFU? Fetch 4 bytes and load into shifter Feed into MBR1 and MBR2 Whenever PC is changed, IFU must be changed

14 instn*0.4 = 5.6 nanosec 5.6/9.2 = x/100 x = 60.87sec ILOAD(6) IADD(4) ISTORE(7) 23microinstructions *0.4nsec = 9.2 nsec 2.5GHz means 1 cycle / (1 / 2.5* G)sec = 0.4nanosec Main PC = PC +1; fetch; go to (MBR) Iload1 H=LV Iload2 MAR=MBRU+H; rd Iload3 MAR=SP=SP+1 Iload4 PC = PC +; fetch; wr Iload5 TOS = MDR; go to main Iload1 MAR = LV + MBR1U;rd Iload2 MAR=SP=SP+1 Iload3 TOS=MDR;wr;goto(MBR1) as in Fig. 4-30 pp282-283 ILOAD(3) IADD(3) ISTORE(5) 23microinstructions *0.4nsec = 9.2 nsec 2.5GHz means 1 cycle / (1 / 2.5* G)sec = 0.4nanosec 14 instn*0.4 = 5.6 nanosec 5.6/9.2 = x/100 x = 60.87sec

11 Write microcode for POPTWO Pop1 MAR = SP -1; rd Pop2 Pop3 TOS = MDR; goto Main PopTwo1 SP=SP−1 PopTwo2 MAR=SP=SP−1; rd PopTwo3 PopTwo4 TOS=MDR; gotoMain1

12 loading locals 0- through 4 Special 1 byte opcodes for loading locals 0 to 3 onto the stack instead of ILOAD. How should modify IJVM to make the best use of it. Local 0 is the link pointer, (rarely used) Let LV point first local variables as an offset( -1)

13 ISHR (Arithmetic Shit Right) Use top two values, replacing with one value, Second word is operand to be shifted. It should be shifted between o-31 depending on the value of first Opcode for ISHR is 122 (0x7A) What is the arithmetic operation equivalent to shit right with a count of 2? Write microcode. Extra: due Nov. 29th ? 00000…1101 000000…110 0000000…11 00000000…1 13 3 Floor(fisrst)/2second

14 ISHL Fisrst*2second

It needs to know how many parameters. Why? 15 INVOKRVIRTUAL It needs to know how many parameters. Why? Compute the base address of the new local variable frame by subtracting off the number of parameters from the stack pointer and setting LV to point to OBJREF

16 DLOAD in Mic-2 dload1 MAR = LV + MBR1U; rd dload2 H = MAR + 1 dload3 MAR = SP = SP +1; wr dload4 MAR = H; rd dload5 MAR = SP = SP + 1; wr dlaod6 TOS = MDR; goto (MBR)

17 finite state machine

18 equivalents?

19 finite state machine

20 IFU with a 5 byte shifter register

21 larger shifter for IFU

22 Mic 2 : go to

23 speed with Mic-2

24 Mic-4

25 two level cache

26 3 way cache?

27 pipeline

28 prefetch

29 cycle 6

30 dependency in pipeline

31 Rewrite Mic-1 intepreter

32 write simulator