1. Fall 2002INEL 4206 Microprocessors Lecture 4 1 Easy I Control Unit (Level 3 Flowcharts) DI → ABUS → AO fetchop1 FetchOp 00 11x opcode aoprsoprloadstorebrnjump 00 00x00 10000 10100 01000 011 AO → EAB EDB → DI branch on opcode fetchop2

2. Fall 2002INEL 4206 Microprocessors Lecture 4 2 Easy I Control Unit State Transition Table (Part I) Curr State opcodeIAC:1 5 Next State ALU op Mem OP PC sel PC is DI le AC le AO se l AO le EDB sel reset1xx xxxxxreset2XXXNOP01X00X0X reset2xx xxxxxfetchXXXNOP1010001X fetch00 00x1xfetchopXXXNOP11X10X0X fetch00 00x0xsoprXXXNOP11X10X0X fetch00 0100xbrn1XXXRD11X10X0X fetch00 0110xjumpXXXRD11X10X0X fetch00 1000xstore1XXXRD11X10X0X fetch00 1010xload1XXXRD11X10X0X fetch00 11x0xaoprXXXRD11X10X0X aopr00 110xxfetchANDNOP1010101X aopr00 111xxfetchADDNOP1010101X sopr00 000xxfetchNOTBNOP1010101X sopr00 001xxfetchSHRBNOP1010101X

3. Fall 2002INEL 4206 Microprocessors Lecture 4 3 Easy I Control Unit State Transition Table (Part II) Current State opcodeIAC: 15 Next State ALU op Mem OP PC sel PC is DI le AC le AO sel AO le EDB sel store1xx xxxxxstore2XXXNOP11X0011X store2xx xxxxxstore3XXXWR10100011 load1xx xxxxxload2XXXNOP11X0011X load2xx xxxxxload3XXXRD11X10X0X load3xx xxxxxfetchANOP1010101X brn1xx xxxx0fetchXXXNOP1010001X brn1xx xxxx1brn2XXXNOP1010001X brn2xx xxxxxfetchXXXNOP1000011X jumpxx xxxxxfetchXXXNOP1000011X fetchop1xx xxxxxfetchXXXNOP11X0011X Can share this state

4. Fall 2002INEL 4206 Microprocessors Lecture 4 4 Easy-I Control Unit StateEncoding reset1 0000 reset2 0001 fetch 0010 aopr 0011 sopr 0100 store1 0101 store2 0110 store3 0111 load1 1000 load2 1001 load3 1010 brn1 1011 brn2 1100 jump 1101 fetchop1 1110 OperationCodeOutput A000A NOTB001not B AND010A and B ADD011A + B SHRB100B / 2 4-bit Encodings for States ALU Operation Table We know how to implement this ALU ! OperationCode NOP00 ReaD01 WRite10 Control Bus Operation Table